Final answer:
Distance running is most likely to improve muscular endurance while sprinting and throwing a fastball primarily improve muscle strength. Hence, option (A) is correct.
Step-by-step explanation:
Of the activities listed, distance running is most likely to improve muscular endurance.
Muscular endurance is the ability of a muscle to continue contracting over a long time without getting tired. Aerobic exercises, such as distance running, increase muscular endurance and cardiovascular health. Distance running requires sustained effort for an extended period, which helps to build endurance in the leg muscles.
On the other hand, sprinting is an anaerobic exercise that primarily improves muscle strength rather than endurance. Sprinting involves short bursts of intense activity, which is more focused on explosive power than prolonged endurance.
Throwing a fast ball, while it requires strength and skill, is also a short-term explosive activity that primarily improves muscle strength rather than endurance.