Which one of following is known as pace maker of endocrine gland?

Thyroxin is secreted by thyroid gland (the largest gland), situated in neck region. Thyroxine regulates the metabolic rate, thus, called as pacesetter of the body. If there's more of thyroxine present in the blood, processes take place at a faster rate, energy is utilized at a faster rate, and if the amount of thyroxine secreted is less than required, the processes of the body take place at a slower pace, lesser energy utilization. Thus, functioning of thyroid gland has major effect on all the organs of our body.