GRE Reading Comprehension: ETS-GRE阅读ETS - TF2RIG566H3ZM01C7

It can be inferred from the passage that which of the followings is true about Asterionella plants in Lake Windermere? A. They are not present except in early spring. B. They contribute silica to the waters as they grow. C. They are food for other organisms. D. They form a silica-rich layer on the lake bottom. E. Their growth peaks in the spring.