Skin covering the __________ has sweat glands but no sebaceous glands.

A. forearm:The forearm has both sweat glands and sebaceous glands. Sebaceous glands are associated with hair follicles and are widely distributed across most of the body surface except for a few regions.

B. back:The back has abundant sebaceous glands along with sweat glands, which contribute to oily skin and acne formation in this area.

C. fingertips:Fingertips have sweat glands, particularly eccrine glands that help with grip and thermoregulation, but they lack sebaceous glands because there are no hair follicles in this region.

D. abdomen:The abdomen contains both sweat glands and sebaceous glands, distributed alongside hair follicles and skin structures.

E. buttocks:The buttocks also have both sweat and sebaceous glands, particularly around hair-bearing areas of skin.

A. fibroblasts:Fibroblasts are connective tissue cells responsible for producing extracellular matrix and collagen. They are not part of the epithelium and do not enhance absorptive surface area.

B. thin and permeable:While simple columnar epithelium is relatively thin to allow some absorption, this characteristic alone does not significantly increase surface area for efficient nutrient uptake.

C. dense microvilli:Microvilli are finger-like projections on the apical surface of simple columnar epithelial cells. Their dense arrangement forms the brush border, greatly increasing surface area and enhancing absorption in the small intestine.

D. cilia:Cilia are hair-like structures that move substances across the epithelial surface, such as mucus in the respiratory tract. They do not increase surface area for absorption and are not a feature of absorptive digestive epithelium.