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
Male with patchy loss of scalp hair and grey hair in the eyebrows and beard diagnosis is 
Select and explain. 
A. Anagen effluvium, B. Alopecia areata, C. Telogen effluvium, D. Androgenic alopecia
B: Alopecia areata
Answer: B: Alopecia areata 
Explanation: B i.e. Alopecia areataSingle or multiple circumscribed smooth patchy hair loss, most obviously on scalp but frequently involving any hair bearing skin eg beard, eyebrows, eye lashes, with pathognomic "exclamation mark" & "going gray overnigth" phenomenon ( i.e., white or gray hairs are frequently spared)Q indicate the diagnosis of alopecia areata. Scanty stumps form 'Exclamation mark (!) in alopecia areata