The correct answer is C. He warned her calmly that he would shoot her if she didn’t keep quiet.
The sentence “If you don’t keep quiet I shall shoot you, ” he said to her in a calm voice” is a threat. The speaker is warning the listener that they will be shot if they do not keep quiet. The speaker is doing this in a calm voice, which suggests that they are serious about their threat.
Option A is incorrect because it does not accurately reflect the content of the sentence. The speaker is not telling the listener to shoot themselves, they are threatening to shoot the listener.
Option B is incorrect because it does not accurately reflect the tone of the sentence. The speaker is not saying that they will shoot the listener, they are warning them that they will shoot them.
Option D is incorrect because it does not accurately reflect the structure of the sentence. The speaker is not telling the listener to be quiet, they are warning them that they will be shot if they do not keep quiet.