How does an increase in metabolic rate affect body temperature?

An increase in metabolic rate raises body temperature primarily because metabolism involves biochemical reactions that produce heat as a byproduct. When the body metabolizes nutrients and oxygen to generate energy, these reactions occur in the body's cells, resulting in heat production. This process is essential for maintaining homeostasis and is particularly significant during physical activities or under metabolic stress, as the energy expenditure increases.

Additionally, hormones such as thyroxine and adrenaline, which can elevate metabolic rate, also contribute to increased heat generation. As cells become more active in terms of metabolic processes, the demand for energy rises, and thus more heat is released into the body. This is why activities that ramp up your metabolism, such as exercise, typically lead to an increase in body temperature, reflecting the heightened activity within the body's systems to sustain energy production and overall function.

The other choices do not relate accurately to the established relationship between metabolic rate and body temperature.