Passage (Science)

Coral reefs cover less than one percent of the ocean floor, yet they support about a quarter of all marine species. Reefs are built by tiny animals called polyps, which form partnerships with algae living inside their tissues. When the water becomes too warm, polyps expel the algae, turning the coral white and leaving it vulnerable to starvation. This process is known as bleaching.

Question

According to the passage, why does coral turn white?

Options

• (A) It absorbs minerals from warm water.
• (B) The polyps die immediately.
• (C) Polyps expel the algae living in their tissues.
• (D) The algae multiply too quickly.

Answer

(C) Polyps expel the algae living in their tissues.

Solution

1. This is a detail question, so find the sentence about turning white.
2. The passage says that when the water becomes too warm, polyps expel the algae, turning the coral white.
3. The passage says the coral is left vulnerable to starvation, not that the polyps die immediately.