Which is a possible reason for the transition of algae from unicellularity to multicellularity?

A.
The transition to multicellularity enabled algae to receive nutrients through the process of photosynthesis.
B.
Through multicellularity, algae were able to move spontaneously in wet environments and find additional sources of nutrients.
C.
The evolution of multicellularity allowed algae to develop traits that kept them close to the land and thus a source of nutrients.