Phytoplankton would most likely be found _______.

Eliminate incorrect options: Phytoplankton cannot survive on the ocean floor in deep aphotic zones because there is no sunlight. Similarly, they are not found inside the bodies of aquatic mammals or in terrestrial forest ecosystems, as these environments do not support their photosynthetic needs.

Identify the correct habitat: Phytoplankton are most likely found near the surface of aquatic biomes where sunlight penetrates, as this is the only environment that meets their requirement for photosynthesis.