This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General, Subject name: Skin
"Going white overnight," is feature of: 
Select and explain. 
A. Vitiligo, B. Alopecia areata, C. Anagen effluvium, D. Albinism
B: Alopecia areata
Answer: B: Alopecia areata 
Explanation: Ans. b. Alopecia areataAlopecia areata typically spares white or grey hair.Hence, if alopecia areata progresses rapidly; it will lead to this phenomenon called "going white overnight" as in a person with a mixture of grey and pigmented hair only grey hair is spared.