A、150. B、15,000. C、1,500. D、5,000. C短文中明确提到There are 1,500 chimps used for research in the U.S.。

Many animals are used to help scientists find out what will happen to people when they take new drugs. Many chimpanzees are kept in research labs for these experiments.
    Chimpanzees look like us, and sometimes even act like us. They are close relatives of ours. That’s why some people say that chimps should be treated differently than other laboratory animals when they are no longer needed.
    One doctor says "you can’t just kill them ...". They shouldn’t be put to sleep just because they are no longer needed.
    There are 1,500 chimps used for research in the U.S. This is more than we need. One group says we should make sure there are no more baby chimps and provide long term care for the rest.
    Scientists were going to use the chimps to study the AIDS virus. The chimps were net a good match and the scientists don’t want to pay to keep the chimps.
    Many chimps still have 30-40 years to live. Some of the chimps have been given to zoos.
    Animal rights groups think chimps should have a natural habitat like the way wild chimps live. They should be with other chimps and be outside everyday. This could cost the government $7 million a year.
    Scientists say the chimps are worth it because they have taught us so much about people.