Meaning: 'From' indicates the origin or source of something, in this case, the benefits that men may receive due to increased aerobic exercise.

Wrong options:

• of: The preposition 'of' indicates possession or belonging, which does not convey the idea of receiving benefits in this context.
• if: The word 'if' introduces a conditional clause, which does not fit the structure of the sentence that discusses benefits directly.
• in: The preposition 'in' typically indicates location or position, which is not appropriate here as it does not express the source of benefit.

Correct answer: developing

Explanation: The gerund 'developing' fits grammatically as it follows the preposition 'to' and indicates the action of becoming affected by the disease, aligning well with the context of risk reduction.

Meaning: 'Developing' means to start to experience or show signs of something, in this case, the disease being discussed.

Wrong options:

• evading: The verb 'evading' means to avoid or escape, which does not fit the context of discussing the risk of acquiring a disease.
• constructing: The verb 'constructing' means to build or create, which is unrelated to the context of disease risk.
• sustaining: The verb 'sustaining' means to maintain or support, which does not accurately convey the idea of becoming affected by a disease.

Correct answer: boost

Explanation: The verb 'boost' is appropriate here as it means to increase or enhance, fitting grammatically and contextually as it describes activities that improve fitness levels.

Meaning: 'Boost' means to increase or improve something, in this case, the level of cardiorespiratory fitness.

Wrong options:

• mitigate: The verb 'mitigate' means to make less severe, which does not align with the idea of increasing fitness levels.
• unravel: The verb 'unravel' means to untangle or solve, which is not relevant to the context of enhancing fitness.
• obtain: The verb 'obtain' means to acquire or get, which does not convey the idea of improving fitness levels.

Correct answer: involve

Explanation: The verb 'involve' is suitable as it indicates participation or engagement, fitting grammatically and contextually as it describes the requirement for activities to engage both body parts.

Meaning: 'Involve' means to include or engage someone or something in an activity, in this case, both the lower and upper body during exercise.

Wrong options:

• input: The noun 'input' refers to something put in, which does not fit the context of physical activity requirements.
• invent: The verb 'invent' means to create or devise, which is unrelated to the context of physical activity engagement.
• infer: The verb 'infer' means to deduce or conclude, which does not match the context of physical activity requirements.

Correct answer: cautioned

Explanation: The verb 'cautioned' is appropriate as it indicates a warning or advice, fitting grammatically and contextually as experts are advising caution regarding the need for further research.

Meaning: 'Cautioned' means to warn someone about potential dangers or issues, in this case, the need for more research.

Wrong options:

• resolved: The verb 'resolved' means to settle or find a solution, which does not fit the context of advising caution.
• dictated: The verb 'dictated' means to prescribe or command, which does not convey the idea of giving a warning or advice.
• violated: The verb 'violated' means to break or disregard, which is not relevant to the context of expert advice.