Meaning: 'Cardiovascular health' indicates how well the heart and blood vessels function, which is crucial for overall fitness.

Wrong options:

• psychological resilience: 'Psychological resilience' refers to mental strength and adaptability, which, while important, does not fit the context of physical health improvements directly related to exercise.
• metabolic rate: 'Metabolic rate' is a measure of how quickly the body uses energy, but it is not the primary focus of this particular sentence about cardiovascular benefits.
• flexibility: 'Flexibility' refers to the range of motion in joints and muscles, which is a benefit of exercise but not the main focus in this context.
• energy levels: 'Energy levels' indicate how energetic a person feels, which is a result of exercise but does not specifically address the heart and blood vessels.

Correct answer: metabolic rate

Explanation: The phrase 'metabolic rate' refers to the speed at which the body converts food into energy. This fits grammatically as it serves as the object of the verb 'increasing,' and contextually, it is relevant to the discussion of weight management through exercise.

Meaning: 'Metabolic rate' is the rate at which the body burns calories and uses energy, crucial for weight management.

Wrong options:

• cardiovascular health: 'Cardiovascular health' is not relevant here as it pertains to heart health rather than the rate of metabolism.
• psychological resilience: 'Psychological resilience' does not relate to physical processes of energy use and is therefore not suitable in this context.
• flexibility: 'Flexibility' refers to the physical ability to stretch, which does not pertain to metabolic processes.
• energy levels: 'Energy levels' describe how energetic someone feels, but they do not specifically address the metabolic processes involved in weight management.

Correct answer: immune

Explanation: The word 'immune' describes the system that protects the body from infections. It fits grammatically as it is an adjective modifying 'system,' and contextually, it aligns with the benefits of exercise in enhancing health.

Meaning: 'Immune' refers to the body's defense system against diseases and infections.

Wrong options:

• psychological resilience: 'Psychological resilience' pertains to mental health and does not fit in the context of physical health benefits related to exercise.
• metabolic rate: 'Metabolic rate' is not relevant here as it refers to energy conversion rather than the body's defense mechanisms.
• cardiovascular health: 'Cardiovascular health' focuses on heart health, which is not the subject of this sentence about immune function.
• discipline: 'Discipline' refers to self-control and habits, which does not relate to the immune system.

Correct answer: discipline

Explanation: The term 'discipline' refers to the ability to maintain consistent habits, which fits grammatically as a noun that serves as the object of the verb 'encourages.' Contextually, it aligns with the idea of developing healthy habits through an active lifestyle.

Meaning: 'Discipline' refers to the practice of training oneself to follow rules or a code of behavior, crucial for maintaining healthy habits.

Wrong options:

• psychological resilience: 'Psychological resilience' does not fit as it pertains to mental strength rather than the development of habits.
• metabolic rate: 'Metabolic rate' is unrelated to the concept of discipline and habit formation.
• cardiovascular health: 'Cardiovascular health' focuses on physical health rather than the behavioral aspect of maintaining habits.
• flexibility: 'Flexibility' refers to physical adaptability, which does not relate to the concept of discipline in lifestyle choices.