Please answer the following question: I'm taking a test and have to guess the right answer to the question after the article. Article: Many people think the dinosaurs were the biggest animals that ever lived. They are wrong. The world's biggest animal is still living and it lives in the ocean . It is the blue whale . Blue whales can be as long as 30 meters and weigh as much as 1,000 kilos. The largest dinosaurs weighed only 500 kilos. The whale is not only the world's biggest animal; it is also one of the cleverest. We know that whales can talk with each other, but we do not know what they are saying. Maybe one day we will learn how to talk with whales, and then they will be able to tell us about themselves. Whales live in the ocean, but they don't _ eggs like fish do. They are mammals . They give birth to babies and have milk inside their own bodies to feed them. Humans are also mammals. Sadly, there are not many kinds of whales left. People have killed them for food and other things for a long time. Now there are laws to stop people killing most kinds of whales. So maybe there will be more of them in years to come. Question: There are not many kinds of whales left because _ Options: A: they don't lay eggs B: people have killed them C: they live in the ocean D: there are laws against them
A:
B