'Exclamation mark' hair is a feature of -

Ans. is 'c' i.e., Alopecia areata Exclamation mark is a feature of Alopecia Areata.Alopecia areata manifests as completely asymptomatic localized areas of alopecia from which all or most of the hairs have been lost.The key to the diagnosis of Alopecia areata isNo itchingNo scalingNo scarringDue to these features it can be easily distinguished from other diseases which cause localized areas of alopecia.Presence of Exclamation mark hairs '7/i nearly a third of the patients, the hair shaft develops a node of trichorrhexis 5-70 mm from the root at which the hair breaks off leaving behind a small fragment of each of these hairs in the patch. Such hair are called exclamation mark hairs".