A、Because of nuclear waste. B、Because of the war. C、Because of environment pollution. D、Because of hunters’ continuing whaling.

Most people are aware, that the earth is a delicate thing, and that it cannot last forever, if we do not take care of it. Apart from the dangers of blowing each other up, there is the problem of pollution of the environment, and the destruction of wild life by hunters.
    Many species of whales, for example, are in danger of extinction because of hunters who continue whaling despite the world’s attempts to limit the annual catch. Seals are also threatened; and with the increasing use of nuclear power to generate electricity, a new danger has arisen: the pollution of oceans by nuclear waste.