Which glands are likely to be active during physical exercise or high temperatures?

The answer is based on the physiological functions of the glands in question, particularly in relation to temperature regulation and the body's response to physical activities.

Eccrine glands are the primary sweat glands responsible for thermoregulation. They secrete a watery sweat directly onto the skin's surface, which helps cool the body down when physical activity occurs or in response to high temperatures. This process is crucial for maintaining an optimal body temperature and is highly active during exercise, as the body’s core temperature rises.

While sebaceous glands do produce an oily secretion that can help condition the skin and hair, they are not primarily involved in thermoregulation or active sweating during physical exercise. Apocrine glands, on the other hand, become active in response to stress and emotional stimuli rather than to thermal regulation from exercise. These glands contribute to body odor since their secretions, which contain proteins and fatty acids, are broken down by skin bacteria.

Thus, eccrine glands are the most relevant to the context of the question, as they are uniquely designed to help cool the body through sweat production during physical exertion or in high heat conditions.