Final answer:
Brisk walking is the most beneficial for cardiovascular health among the activities, as it is an aerobic exercise known to significantly reduce heart-related risks.
Step-by-step explanation:
You asked which of the listed activities contributes the most to John's cardiovascular health. The answer is a. Brisk walking.
Among the activities John performs, brisk walking is classified as an aerobic exercise that enhances cardiovascular health. Studies have demonstrated that engaging in aerobic activities like walking can have significant benefits for the heart and overall health. In fact, 30 minutes of such exercise can drastically reduce the risk of a heart attack by nearly 50%.
The American Heart Association recommends at least 20-30 minutes of aerobic exercise 3-5 times a week to maintain good cardiovascular health. Aerobic exercises increase muscular endurance and the efficiency of the heart and lungs, making them crucial for maintaining a strong cardiovascular system.