Final answer:
An increase in metabolic rate triggers the body to cool down via stimulation of sweat glands and dilation of blood vessels. The correct answer, therefore, is stimulation of sweat glands and vasodilation in blood vessels of the skin (option B).
Step-by-step explanation:
The question revolves around the mechanisms our body employs to regulate temperature. An increase in metabolic rate results in a higher body temperature; thus, to cool down, the body triggers thermoregulatory responses. In particular, the correct response would involve stimulation of sweat glands and vasodilation in blood vessels of the skin. This means that choice B, stimulation of sweat glands and vasodilation in blood vessels of the skin, is the correct answer.
As we engage in strenuous activities or undergo an increase in metabolic rate, our internal thermostat adjusts. The brain sends signals that lead to increased sweat production, and it commands the dermal blood vessels to dilate. This dilation increases the amount of blood and heat that travel to the skin's surface, where heat can be released to the environment, thereby cooling the body down. This process is part of the body's efforts, together with the cardiovascular system, to maintain body temperature.