The relative pronoun who is specifically used to refer to people or persons. In this context, it identifies the individual who performed the action of speaking.

১. Option A/C use that which is acceptable but who is more precise for humans.
২. Option D uses which which is strictly reserved for objects or animals.
৩. The relative clause who said that correctly modifies the subject the man.

অতিরিক্ত তথ্য: Using correct relative pronouns helps in creating clear and professional sentences.