Final answer:
The energy required for cellular activities within a specific time frame is called the metabolic rate, with the basal metabolic rate (BMR) being a key component that varies based on several factors including muscle mass and physical activity levels. The correct option is B. metabolic rate
Step-by-step explanation:
The amount of energy required to fuel cellular activities within a specified period of time is known as the metabolic rate. The basal metabolic rate (BMR) is the total energy conversion rate of a person at rest and accounts for the energy consumed for the body's basic functions such as those of the liver, spleen, and brain.
Vigorous exercise significantly increases the energy consumption of skeletal muscles and the heart. Factors affecting BMR include age, gender, body weight, and muscle mass. Lean muscle mass burns more calories than body fat, which is why athletes often have a higher BMR. The correct option is B. metabolic rate