Insert the missing word: ______ shall I say is calling?

• In the above subject, there is use of pronouns, and pronouns are used depending on what the sentence represents a subject or an object.- Anyway, in the above sentence, the sentence represents to subject not an object, therefore "who" is used.- Pronouns are usually used instead of a noun or a noun phrase. A pronoun is used instead of a noun when needed. For example, mine, yours, ours, who, whom, etc.,The sentence "Who shall I say is calling?" is used to ask for the identity of the caller.Whose: This is a possessive form used to ask about ownership, such as "Whose book is this?" It doesn't fit in this context because we're asking for the caller's identity, not about possession.Who's: This is a contraction of "who is" or "who has." While it might seem like it could work, it doesn't fit grammatically in the sentence structure. "Who's shall I say is calling?" would not make sense.Who: This is the correct choice because "who" is used to ask about a person or people. The sentence "Who shall I say is calling?" is grammatically correct and properly structured to ask for the identity of the caller.