Phagocytosis Provides a Means by Which Heterotrophic Protists Can Take

Phagocytosis provides a means by which heterotrophic protists can take in food particles. In what way do photosynthetic protists reflect phagotrophy?

A) Photosynthetic protists do not reflect phagotrophy, as these cells fix carbon dioxide into sugars and do not require particulate matter as a source of carbon.
B) Phagotrophy is the process by which cyanobacteria were introduced into protistan cells, to become endosymbionts and, eventually, chloroplasts.
C) Evolutionary loss of the ability to take in particles by phagotrophy forced some protists to evolve a capacity for photosynthesis.
D) Phagotrophy introduces carbon dioxide into the cells of photosynthetic algae where it gets reduced to form sugars.