The correct answer is D. The Captain said to his men, “Stand at ease.”
The other options are incorrect because they do not use the imperative mood, which is the mood used to give commands. In option A, the Captain is commanding his men, but he is not using the imperative mood. In option B, the Captain is stating a fact, not giving a command. In option C, the Captain is giving permission, not giving a command.
The imperative mood is used to give commands, make requests, or offer suggestions. It is the most direct form of speech, and it is often used in formal settings, such as when giving orders in the military or when giving instructions in a classroom.
In the sentence “The Captain said to his men, ‘Stand at ease,'” the Captain is using the imperative mood to give a command to his men. He is telling them to stop what they are doing and to relax. The use of the imperative mood makes it clear that this is a command, not a suggestion.