Suppose that you use direct calorimetry to monitor a person enclosed in a small room. During the measurement the person lowers many heavy weights from a desk onto the floor. The heat production you measure will

A) slightly underestimate the person's metabolic rate.
B) slightly overestimate the person's metabolic rate.
C) precisely and directly measure the person's metabolic rate.
D) be unrelated to the person's metabolic rate.