The correct option is C Who
Option A is the correct answer as ‘who’ is a relative pronoun used for people. A relative pronoun is used to connect a clause or phrase to a noun or pronoun. Here, ‘who’ connects the noun ‘man’ to the clause ‘had been married ten times before.’ As, ‘who’ also acts as the subject of the clause ‘had been married ten times before,’ it is the nominative or subjective case of relative pronoun. Option D cannot be used as ‘whose’ is the possessive form of ‘who’ and is used when some kind of possession is shown. As this sentence does not talk about people or animals possessing or owning something, ‘whose’ cannot be used here. Option B cannot be used as ‘which’ is the relative pronoun used for things. Option C cannot be used as ‘where’ is used for place.