Final answer:
Merocrine (eccrine) sweat glands are most abundant on the skin's surface, especially on the hands, where they play a key role in thermoregulation and homeostasis.
Step-by-step explanation:
Merocrine sweat glands, also known as eccrine sweat glands, are found all over the skin's surface and are particularly abundant in areas involved in thermoregulation such as the hands. These glands are responsible for producing a hypotonic sweat that aids in regulating body temperature and maintaining homeostasis. When answering which area has the most abundant merocrine sweat glands, the correct answer is D, the hands. Unlike apocrine sweat glands, which are found in densely hairy areas and are associated with body odour, eccrine glands secrete a watery sweat that consists mostly of water, some salts, antibodies, and metabolic waste.