Answer:
A. The whale is heterotrophic.
Step-by-step explanation:
The whale is an aquatic animal that is heterotrophic in nature. Heterotrophic means that this animal lacks the ability to manufacture its own food because it depends on plants and animals as a source of food energy. Since the Whale is dependent on phytoplankton for food, this means that it is not a producer of food and as such is heterotrophic.
Phytoplankton is a marine alga. Algaes are prokaryotes and this means that they are unicellular animals without a membrane-bound nucleus. The Cell wall is mostly a characteristic of plants. So the first option is a perfect description of the whale and not its food source which is the phytoplankton.