Topic: Pronoun (সর্বনাম),

Best Answer Explained in Below-:

The phrase "It was I - he wanted to sing to" requires an object pronoun to indicate the person receiving the action of the verb "sing." In this context, "whom" is the correct choice because it serves as the object of the verb "sing" within the relative clause.

When we analyze the sentence structure, "he wanted to sing to whom" implies that we are referring to the individual who is being sung to. "Whom" is specifically used when referring to the object of a verb or preposition, as it denotes the person affected by the action.

Let’s briefly consider the other options: "that" would normally introduce a defining relative clause but does not serve as the object in this case. "Whose" indicates possession, which is not applicable here, and "what" does not fit since it refers to things or ideas rather than people. Therefore, "whom" is the only option that correctly fulfills the grammatical role of the object in this sentence, making it the appropriate choice.