Answer:
The correct answer is D. Dinoflagellates-feed on dead organic matter
Step-by-step explanation:
Dinoflagellates are usually autotroph so they have photosynthetic pigments. When they're heterotrophs they usually are parasites or establish endosymbiotic relationships with algae or others. It's not absolutely impossible that they feed on the dead organic matter but it's not common, while all the other options are completely true for each organism of the groups mentioned.