What is the definition of a scientific theory?

Why do carbohydrate molecules function so well as fuel for the body?

The pharynx is the structure in the body that serves as a pathway of both air and food. how does the body make sure that food does not get into the lungs? the salivary glands secrete enzymes that pull food out of the air pathway. the small intestine pushes the air out of the digestive system. the pancreas breaks down food in the air pathway. the epiglottis closes the air pathway so that food will not enter it.

In the diagram below, the northern hemisphere would be in what season at position a a. fall b. winter c. summer d. spring