Which of the following is a function of the thyroid gland?

The thyroid gland plays a crucial role in regulating the body's metabolism, and one of its primary functions is to set the basal metabolic rate (BMR). The BMR is the amount of energy expended while at rest in a neutrally temperate environment. It is influenced by hormones produced by the thyroid gland, primarily thyroxine (T4) and triiodothyronine (T3). These hormones increase the rate of metabolism in cells, promoting processes such as the conversion of nutrients into energy and the regulation of heat production.

In contrast to the other options, the thyroid does not directly regulate blood pressure, produce insulin, or control the immune response. Blood pressure regulation is primarily managed by the cardiovascular system and involves hormones like adrenaline, while insulin is produced by the pancreas to control blood glucose levels. The immune response is primarily regulated by components of the immune system such as white blood cells, rather than the thyroid gland. Thus, the correct answer highlights the essential role of the thyroid in metabolic regulation, demonstrating its influence on overall energy expenditure in the body.