Concept:A sentence that asks a direct question must end with a question mark.Explanation:The given sentence is "Who did Gopi marry _".It begins with the question word "Who".Wh-word questions are called interrogative sentences.An interrogative sentence always ends with a question mark (?).Therefore, the blank must be filled with a question mark.The complete sentence is: Who did Gopi marry?Answer:Option A — ? (question mark)