Question

what is the main idea of this selection? a california sea otters were once nearly extinct but have slowly increased in number since the early 20th century. b the eating habits of california sea otters play an important role in both their survival and the health of the coastal ecosystem. c researchers have discovered that northern sea otters are more numerous than california sea otters because of differences in hunting laws. d california sea otters use tools such as rocks to open shells, which makes them unique among marine mammals.

Explanation:

The passage likely discusses various aspects of California sea - otters. Option A only mentions population change. Option C focuses on differences between northern and California sea - otters in hunting laws. Option D is about a unique behavior of using tools. Option B emphasizes the role of California sea - otters in the coastal ecosystem regarding survival and health, which is a comprehensive main idea encompassing more aspects of their significance.

Answer:

B. The eating habits of California sea otters play an important role in both their survival and the health of the coastal ecosystem.