To accurately identify the purpose of paragraph 9, the context of the paragraph is essential. Assuming that paragraph 9 discusses the use of bioluminescence or organism-specific examples, the most likely purpose could be inferred from the options provided.
If the paragraph focuses on a specific organism and its mating behavior linked to bioluminescence, then the best choice would be:
D. to provide an example of an organism that uses bioluminescence to attract a mate.
If the paragraph discusses other aspects, you would choose accordingly based on the content.