Answer:
The correct answer is option A - increased heart size.
Explanation:
Cardiovascular endurance activities or cardio-respiratory exercise can improve body ability by using large muscles like respiratory apparatus. Long term effect of cardio-respiratory exercise helps the hear and lungs to increase the supply of the oxygen and nutrients to the muscles for better function. These exercises help in increasing heart size by practicing moderate to high intensity for a long time.
Thus, the correct answer is option A. increased heart size.