Emily is developing a computer model of protist populations in certain areas of the ocean, and how they help maintain homeostasis in ecosystems. Photosynthetic protists play essential roles in the environment, especially in oceans and lakes. If a hypothetical catastrophic event drastically reduced the population of zooxanthellae, a photosynthetic protist with a specific habitat, which statement describes the most likely result?

As the question is incomplete and there are no statements available based on which the question can be answered. But based on the knowledge it can be answered.

Most of the corals contains photosynthetic algae which are known as zooxanthllae which lives in the tissues of the corals. Algae and corals have mutualistic relationship.

The corals provide algae space to live and algae provides coral  food such as glucose and glycerols to them which are considered as products of photosynthesis.

If the producers are hampered by the catastrophic event then the main source of the food will be hampered. There will be less or no food source for the corals which covers a large area in the marine ecosystem.

There are chances that there will be more load on the other photosynthetic organism in water as there will be more population dependent on them for food.

Hence, if there is a loss of habitat for these protist other levels of food chain will be affected due to inter connection.

the answer is

c. parental