Final answer:
BMR is typically measured by calculating oxygen consumption, which correlates with energy expenditure while the body is at rest, maintaining vital functions.
Step-by-step explanation:
The basal metabolic rate (BMR) refers to the rate at which the body uses energy while at rest to maintain vital bodily functions. BMR is commonly measured by calculating oxygen consumption, as energy consumption is directly proportional to oxygen consumption.
This is because the process of metabolism, which includes the digestion and oxidation of food, relies heavily on oxygen. When oxygen is used to breakdown food, energy is released as a byproduct. This method of determining BMR is backed by the understanding that approximately 20 kJ of energy are produced for each liter of oxygen consumed, irrespective of the type of food being oxidized.
Therefore, the correct answer to the question 'How did you determine basal metabolic rate (BMR)?' is C. Calculated oxygen consumption. This method reflects the energy expenditure associated with the body's basic functions in a resting state. A variety of factors influence BMR including age, gender, body composition, and physical fitness level. Athletes, for example, tend to have higher BMRs due to larger muscle mass, which burns more calories at rest compared to body fat.