Why are complex carbohydrates, such as starches, considered long-term energy sources? A. The human body can break down complex carbohydrates into sugar molecules that provide energy. B. The human body can break down complex carbohydrates into protein molecules that provide energy. C. Complex carbohydrates contain fatty molecules that release energy slowly. D. Complex carbohydrates contain vitamins and minerals that release energy slowly.

A. The human body can break down complex carbohydrates into sugar molecules that provide energy.

Explanation:

Strings of glucose, form complex carbohydrates such as starch and glycogen. Glycogen which is a stored form of glucose in humans is a source of long-term energy, and a complex carbohydrate because glycogen can be converted to glucose-1-phosphate which can enter the glycolytic cycle to generate Adenosine triphosphate which is a unit of energy.

This stored form of energy can be slowly broken down to release energy when needed by the body. During exercise, for instance, glycogen can slowly release ATP needed for energy.