Final answer:
The thyroid gland is the main gland responsible for raising the basal metabolic rate (BMR) of the body.
Step-by-step explanation:
The main function of thyroid gland is to raise the basal metabolic rate (BMR) of the body. The BMR is the amount of energy consumed by the body at rest, and it is regulated by hormones produced by the thyroid gland. One of these hormones, called thyroxine, speeds up the metabolic activity of the body, resulting in a higher BMR.