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
Disease of sweat gland ? 
Select and explain. 
A. Fordyce's spot, B. Acne vulgaris, C. Fox-Fordyce's disease, D. None
C: Fox-Fordyce's disease
Answer: C: Fox-Fordyce's disease 
Explanation: Ans. is 'c' i.e., Fox-Fordyce's disease