Which of the following is a sign of aging as it relates to the integumentary system?

The loss of subcutaneous fat is a significant sign of aging as it relates to the integumentary system. As individuals age, the body's ability to produce and maintain fat decreases, leading to a reduction in the fat layer beneath the skin. This loss can result in thinner skin that is less pliable, increased fragility, and a greater risk of injury. Additionally, the decrease in subcutaneous fat can affect body temperature regulation and contribute to a more pronounced appearance of wrinkles and sagging skin, both of which are commonly associated with aging.

In contrast, while increased fat distribution and thicker skin may occur in some individuals due to various factors, they are not typical signs of aging related to the integumentary system. Decreased sensitivity to UV rays is also not an aging sign; rather, aging often leads to increased sensitivity and skin damage due to prolonged exposure over time.