Which of the following responses occurs when water temperature is maintained above 90 degrees Fahrenheit?

Maintaining water temperature above 90 degrees Fahrenheit leads to an elevated metabolic rate. When the body is exposed to warmer temperatures, it has to work harder to regulate its internal environment, increasing metabolic processes. This heightened metabolic rate can cause an increase in heart rate and various physiological responses as the body attempts to cool itself and maintain homeostasis.

Additionally, increased metabolic activity leads to greater energy expenditure and can promote a variety of biochemical reactions. In physical activities or aquatic exercises, warm water can enhance muscle relaxation and flexibility, contributing further to the overall elevation in metabolic responses. Hence, the correct choice reflects a fundamental physiological response to sustained exposure to elevated temperatures.