Answer:
D.The pack of wolves returned to its den.
Step-by-step explanation:
When we are referring to an animal or an object, we must not use the pronouns "she / her" or "he / his" as these pronouns are specific to human beings. In this case, animals and objects are referred to with the pronoun "it". The pronoun "our" is also used for a group of human beings and never for a group of animals or objects.
In this case, the letters A, B, and C do not have the correct way to use a pronoun that refers to a pack of wolves. If wolves are animals, the right pronoun for them is "it / its" as shown in the letter D.