This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Skin
Acne vulgaris is caused by- 
Select and explain. 
A. Staph aureus, B. Diphtheroids, C. Sweat gland hyperplasia, D. Obstruction to pilosebaceous duct
D: Obstruction to pilosebaceous duct
Answer: D: Obstruction to pilosebaceous duct 
Explanation: D i.e. Obstruction to pilosebaceous duct