Answer:
I believe the best answer as to why the author uses the classification in this part of the text is:
B) It helps the author identify types of marine mammals.
Step-by-step explanation:
In the passage we were asked to analyze, the author is not necessarily describing what marine mammals are. That was probably established earlier in the text. The author's purpose now is to enlighten readers about the existing types of marine mammals. That is why he/she uses classification: it helps divide the animals into different categories, each category possessing common characteristics. The author does offer some examples to help readers visualize the types of marine mammals, but that is not the main purpose of the passage. The purpose is certainly to identify those types.