Answer
c.
Work Step by Step
Option a. is incorrect. Photosynthetic protists are autotrophs, not heterotrophs.
Option b. is incorrect. Not all photosynthetic protists are closely related to plants. Only the red algae are closely related to plants while other photosynthetic protists are closer to the nonphotosynthetic ones.
Option d. is incorrect. Giant kelp does not play a role in the formation of coral reefs; rather, they house organisms in the coral reef and are a source of food for other organisms there.
Option c. is correct. Phytoplankton consist of photosynthetic protists which are a source of food for organisms that live in oceans and lakes.
