Which of the following describes a type of comedo that is commonly referred to as a blackhead?

A blackhead is specifically classified as an open comedo. Open comedones occur when a hair follicle becomes clogged with sebum and dead skin cells, and the surface of the clogged follicle remains open, allowing the material inside to be exposed to air. This exposure causes oxidation of the melanin in the sebum, resulting in the characteristic dark appearance of a blackhead.

Closed comedones, on the other hand, also involve clogged hair follicles, but the follicle is closed at the surface. This prevents air from reaching the clogged material, resulting in a flesh-colored or white appearance, commonly referred to as whiteheads.

Milia are tiny, white cysts that appear on the skin, usually around the eyes and cheeks, and are not the same as comedones. They are formed when dead skin cells become trapped in small pockets at the surface of the skin.

Comedone is a general term that refers to both open and closed types of clogged hair follicles, but it does not specifically indicate a blackhead. Understanding these distinctions helps in recognizing and treating different forms of acne effectively.