Final answer:
The resting metabolic rate (BMR) is the factor that makes the greatest contribution to total energy expenditure, accounting for about 70% of the daily energy used by the body.
Step-by-step explanation:
The component that makes the GREATEST contribution to total energy expenditure is A) resting metabolic rate (BMR). The BMR describes the amount of energy expended by humans at rest and accounts for about 70 percent of all daily energy expenditure, with the liver and spleen consuming the largest fraction. Factors such as age, gender, total body weight, and muscle mass can influence BMR. Notably, physical activity also raises the basal metabolic rate by building extra lean tissue, which is metabolically active even during rest. Therefore, the resting metabolic rate is the primary factor in total energy expenditure, far outweighing physical activity energy expenditure, the thermos effect of food, or resting blood sugar levels.