Final answer:
A comedo is commonly referred to as a blackhead. It occurs when pores become clogged with sebum and skin cells, resulting in a visible black spot due to oxidation of the sebum when exposed to air. Acne can generally cause various skin disturbances including blackheads.
Step-by-step explanation:
A comedo is commonly called a blackhead. When hair follicles become clogged by shed skin cells and sebum, it causes non-inflammatory lesions known as comedones. These can manifest as both whiteheads and blackheads, where blackheads are open to the air, allowing the oxidation of lipids in sebum which gives them their distinctive black color.
Acne is a prevalent skin disorder, particularly during puberty, but it can also affect infants and continue into adulthood. It is characterized by pimples, blackheads, nodules, or other skin lesions typically on areas of the skin with high concentrations of sebaceous glands, like the face and back. A blackhead is a form of acne where the oxidized sebum appears as a black spot on the skin.
To accurately answer the student's question: A/An comedo is commonly called a blackhead.