Sebaceous gland called oil glands are present in the skin which at the time of puberty cause higher sebum production which cause acne. So at the time of puberty hormonal change occurs and androgen level like testosterone level becomes high in the body.
This high level of androgen cause rise in the production of sebum from sebaceous glands and cause inflammation in that region and allow the colonization of bacteria like <em>Propionibacterium acnes</em> which results in the formation of acne. So hormonal change cause acne therefore the right answer is C.
The curves help the spine absorb stress from body movement and gravity. When viewed from the back, the spine should run straight down the middle of the back.
