Concept:Zihar is a pre-Islamic custom of divorce in which a husband compares his wife to a prohibited relative.Explanation:In Zihar, a man says to his wife that she is like the back of his mother.This makes her permanently unlawful for him unless he performs expiation.It is not based on beating, cursing, or absence of conjugal relations.It is essentially a forbidden comparison of one's wife to one's mother.Answer:B. comparison of one's wife to the back of one's mother