The correct answer is D) answering pennant. When signaling by flag hoist, the answering pennant is used to indicate the completion of the communication. The answering pennant is a distinctive flag that is hoisted to acknowledge the receipt and understanding of the message. This pennant signals that the message has been received and the communication is finished. The other options are incorrect because they do not specifically indicate the completion of the communication. Code flag N and code flag R have other meanings in the International Code of Signals, and signal AR is used to indicate the end of a radio transmission, not a flag hoist communication.