Question

phytoplankton are plant - like microscopic organisms that float in bodies of water such as the ocean. they take in carbon dioxide during the process of photosynthesis. what would most likely happen if the population of phytoplankton was destroyed?
sea temperatures would decrease.
greenhouse gases would increase.
atmospheric oxygen would increase.
sea levels would drastically decrease.

Explanation:

Phytoplankton take in carbon dioxide during photosynthesis. Carbon dioxide is a greenhouse gas. If phytoplankton population is destroyed, less carbon dioxide will be taken in. So, greenhouse gases (carbon dioxide is one of them) would increase. Sea temperatures are related to many factors but not directly in a simple way as described in the first option. Phytoplankton produce oxygen during photosynthesis, so if they are destroyed, atmospheric oxygen would decrease not increase. Sea levels are mainly affected by melting of ice - caps etc., not by phytoplankton population destruction.

Answer:

Greenhouse gases would increase.