It can be inferred from the passage that limestone deposits serve as the basis of________. A. coral reefs B. red algae C. subtropical seawater D. secret passages
Giải thích
Đáp án A
Thông tin ở câu cuối của bài: This type of algae has an essential role in the formation of coral reefs: it secretes lime from the seawater to foster the formation of limestone deposits.