[单项选择]

Imagine fishermen walking down to the seashore, ready to carry out their early morning routine of preparing their boats and net. (51) they hope for a good catch of fish. But to their (52) , a horrible sight meets their still sleepy eyes. Thousands of fish have been washed ashore dead. The cause of this mass destruction—A red tide!
Red tides are a global (53) . They have been observed on both the Atlantic and the Pacific coasts of the United States and Canada. They have also occurred in many other places. Though relatively few people are (54) them, red tides are not new.
In the Philippines, a red tide was first seen in the province of Bataan in 1908. Since then, red tides have been seen in many other (55) . A Philippines red tide expert told us that " (56) the fish kills, the Philippines has documented 1, 926 eases of dead shellfish poisoning caused by red tides. "
The term "red tide&qu
A. applies to
B. sums up
C. copes with
D. leads to