Context: A tropical coral reef is a type of ecosystem in the ocean. Tropical coral reefs are found in warm, shallow water near the equator. They have many large formations called corals. Corals may look like rocks or plants, but they are actually structures made up of living animals and can grow over time.
Corals provide shelter for fish, crabs, eels, and many other organisms. These coral reef organisms are prey for larger animals, such as sea turtles, sharks, and dolphins. Most of these organisms need tropical coral reefs in order to survive and reproduce.

Figure 1: a tropical coral reef.

Figure 2: several types of corals.
Which of the following is a characteristic of tropical coral reefs?
A. They are used by many different organisms.
B. They are usually found in the deep ocean.
C. They have many large rocks called corals.
Choose the right answer from the options and respond with its letter.

A