a, because exercise doesn't just aid the prevention of certain diseases, it helps prevent many diseases. i would've chosen d if it wasn't so specific but a is the correct answer.
There are two kinds of digestion: mechanical and chemical. Mechanical digestion involves physically breaking the food into smaller pieces. Mechanical digestion begins in the mouth as the food is chewed. Chemical digestion involves breaking down the food into simpler nutrients that can be used by the cells.
Answer: In the mouth and pharynx, it consists of skeletal muscle that aids in swallowing.In the rest of the digestive tract, it consists of smooth muscle three layers in the stomach two layers in the small large intestines and associated nerve fibers.
The amount of red blood cell production in bone marrow decreases and storage of mineral minimaxes seeing the doctor is good
