Question

microbes have adapted to survive in many different environmental conditions. in which of the following environments would you likely find a photoautotroph?
environment for photoautotrophs
in the upper layers of the ocean
in \pond scum\ floating on the surface of a
marsh
in the bottom of the ocean
on the surface of an underground lake
not an environment for photoautotrophs

Explanation:

Photoautotrophs use light energy to produce organic compounds from inorganic substances (such as carbon dioxide). They require light for photosynthesis. The upper layers of the ocean receive ample sunlight, "pond scum" floating on the surface of a marsh is exposed to sunlight, and the surface of an underground lake (assuming some light can reach there, maybe through an opening) can have light. However, the bottom of the ocean is typically in darkness (except for some bioluminescent areas which is not relevant for photoautotrophs as they need sunlight for photosynthesis).

Answer:

Environment for Photoautotrophs: in the upper layers of the ocean, in "pond scum" floating on the surface of a marsh, on the surface of an underground lake.
Not an Environment for Photoautotrophs: in the bottom of the ocean.