Which part of total energy expenditure accounts for the highest percentage?

The correct answer is B, Basal Metabolic Rate (BMR), as it accounts for the largest proportion of total energy expenditure in the majority of individuals. BMR refers to the amount of energy the body requires to maintain basic physiological functions at rest, such as breathing, circulation, cell production, and temperature regulation. It typically makes up about 60-75% of a person's total daily energy expenditure, depending on factors like age, sex, weight, and body composition.

In contrast, physical activity, which includes any movement from exercise to daily tasks, usually accounts for a smaller percentage of total energy expenditure, typically ranging from about 15-30%. The thermic effect of food, which is the energy required for digestion, absorption, and metabolism of nutrients, contributes an even smaller percentage, usually around 10%. Thus, BMR is the dominant factor when calculating total energy expenditure.