Final answer:
The average adult's skin covers approximately 19 square feet, taking into account the skin's complex structure with blood vessels, sweat glands, and nerve endings within a 2 mm thick layer.
Step-by-step explanation:
The question on average adult skin covering a certain amount of square feet pertains to the biology of the human body, more specifically the integumentary system. The structures and complexity of the skin are quite remarkable. For instance, just one average square inch of skin contains 20 blood vessels, 650 sweat glands, and over a thousand nerve endings. This dense composition of functional elements all reside within a layer roughly 2 mm thick. Considering the options provided and the context of the human body's anatomy, the correct answer to the question of how much area an average adult skin covers is approximately 19 square feet (b).