I think it would be kidneys because of the way the question is worded, kidneys are the only things you have 2 of that also is involved in the digestion of foods.
Cardiovascular or cardio-respiratory endurance or aerobic fitness, is the ability of the heart and lungs to deliver oxygen to the body's tissues during sustained physical activity. Muscular endurance is the ability of a muscle, or group of muscles, to perform continuously without fatigue. Weight training can be performed with free weights, such as barbells and dumbbells, or by using weight machines to increase the muscular strength.
Answer: appendix is my guess
Explanation:
