Meaning: 'Life-space' means the area or environment where a person lives and interacts, emphasizing the importance of one's surroundings on cognitive health.

Wrong options:

• plagues: 'Plagues' refers to widespread diseases or afflictions, which does not fit the context of living space and is grammatically incorrect as it does not serve as a noun describing a space.
• trails: 'Trails' typically refers to paths or routes, which does not relate to the concept of living space and is not suitable in this context.
• manes: 'Manes' refers to the long hair on the neck of certain animals, which is irrelevant to the discussion of cognitive health and living environments.

Correct answer: condition

Explanation: The word 'condition' is appropriate here as it refers to a state of health, particularly in the context of Alzheimer's disease. It fits grammatically as a noun that describes the health status of the participants.

Meaning: 'Condition' means a particular state of health or a medical issue, in this case referring to Alzheimer's disease.

Wrong options:

• distension: 'Distension' refers to the state of being swollen or expanded, which does not fit the context of cognitive health and is grammatically incorrect as it does not describe a health state.
• kitten: 'Kitten' refers to a young cat, which is completely unrelated to the topic of cognitive decline and does not fit grammatically or contextually.
• imperfection: 'Imperfection' refers to a flaw or defect, which does not accurately describe the medical state being discussed and is not suitable in this context.

Correct answer: increased

Explanation: The word 'increased' is the correct choice as it indicates a rise in risk, fitting grammatically as a past participle that modifies 'risk' in the sentence.

Meaning: 'Increased' means made greater in size, amount, or degree, indicating a higher risk of cognitive impairments for homebound individuals.

Wrong options:

• repeat: 'Repeat' means to do something again, which does not fit the context of risk and is grammatically incorrect as it does not modify 'risk' appropriately.
• screech: 'Screech' refers to a high-pitched sound, which is irrelevant to the context of cognitive health and does not fit grammatically.
• elite: 'Elite' refers to a select group or superior status, which does not relate to the concept of risk and is not suitable in this context.

Correct answer: suggests

Explanation: The verb 'suggests' is appropriate as it indicates a proposal or recommendation made by the investigator, fitting grammatically as a present tense verb that aligns with the context of presenting findings.

Meaning: 'Suggests' means to propose an idea or recommendation, indicating that the investigator is offering a hypothesis about life space and cognitive engagement.

Wrong options:

• consents: 'Consents' means to agree or give permission, which does not fit the context of presenting findings and is grammatically incorrect as it does not convey a proposal.
• questionnaires: 'Questionnaires' refers to a set of questions for gathering information, which does not fit grammatically as a verb in this context.
• neath: 'Neath' is an archaic term meaning beneath, which does not fit grammatically or contextually as it does not serve as a verb.

Correct answer: actively

Explanation: The adverb 'actively' is the correct choice as it describes the manner in which individuals engage with their environment, fitting grammatically as it modifies the verb 'engaging'.

Meaning: 'Actively' means in a way that involves physical or mental effort, indicating that individuals are engaging in cognitive activities.

Wrong options:

• gymnastically: 'Gymnastically' refers to gymnastics or physical exercises, which does not fit the context of cognitive engagement and is grammatically incorrect as it does not modify 'engaging' appropriately.
• candidly: 'Candidly' means in an open and honest way, which does not fit the context of engagement and is not suitable in this context.
• underhandedly: 'Underhandedly' means in a secretive or dishonest manner, which is contrary to the intended meaning of engaging actively.

Correct answer: abilities

Explanation: The noun 'abilities' is appropriate as it refers to the skills or capacities of individuals, fitting grammatically as it serves as the object of the engagement described in the sentence.

Meaning: 'Abilities' means the skills or talents that a person possesses, indicating the cognitive skills that are being challenged and engaged.

Wrong options:

• antipathies: 'Antipathies' refers to strong dislikes, which does not fit the context of cognitive skills and is grammatically incorrect as it does not serve as an object of engagement.
• densities: 'Densities' refers to the degree of compactness of a substance, which is irrelevant to cognitive skills and does not fit grammatically or contextually.
• affinities: 'Affinities' refers to natural liking or sympathy for something, which does not accurately describe cognitive skills and is not suitable in this context.