Final answer:
A. Excessive sebum production
Comedones/follicular hyperkeratosis are primarily caused by excessive sebum production, which leads to clogged hair follicles. These can then become infected with bacteria such as Propionibacterium acnes, resulting in acne.
Step-by-step explanation:
Comedones, commonly associated with acne, are caused by excessive sebum production.
They occur when hair follicles become clogged with sebum and dead skin cells, leading to non-inflammatory lesions such as whitehead and blackhead pimples. The clogging of follicles is exacerbated by an overproduction of sebum, a substance produced by sebaceous glands, which can be stimulated by hormonal changes such as those during puberty. Bacterial infection, particularly by Propionibacterium acnes, contributes to the inflammation and progression of acne. This bacteria consumes components of sebum and releases enzymes that damage the hair follicle, leading to a range of inflammatory lesions. Simple measures such as cleaning the skin daily with a mild soap can help remove excess oil and prevent acne.