What are the types of organisms that make up the marine flora?

I - Phytoplankton are primary producers that float on the water and are capable of photosynthesis.
II - Lichens are a combination of symbiosis between fungi and algae.
III - Algae can be green, red, or brown.
IV - Phanerogams are the large aquatic plants.
a) Only I and II are correct.
b) Only III and IV are correct.
c) I, II, and III are correct.
d) I, II, III, and IV are correct.