A、17,000. B、1,700. C、70,006. D、7,000. D信息明示题，文章提到Last year, coast Guardsmen saved the lives of almost 7,000 people，所以D正确

The Coast Guard does What its name says: it guards the Coasts of the United States. During a war, the Coast Guard becomes part of the United States Navy, and helps to protect against enemy attacks. In times of peace, however, the Coast Guard is part of the United States Department of Transportation. It has responsibility for many different duties. The Coast Guard can be found at many large lakes in America, as well as in coastal waters. It enforces laws controlling navigation, shipping, immigration, and fishing. It enforces other laws that affect the thousands of privately-owned boats in the United States.
    Coast Guard planes, boats and helicopters search for missing boats and rescue people in dangerous situations. Last year, Coast Guardsmen saved the lives of almost 7,000 people.
    The Coast Guard does scientific research on the ocean. It also uses ice-breaking boats to clear ice from rivers or lakes, so boats can travel safely. One of the Coast Guard’s most important duties now is helping to keep illegal drugs out of the United States. Coast Guard boats, armed with guns, use radios and radar to find. boats that may be carrying drags. They stop the boats suspected of carrying drugs and search them. They seize the drugs and arrest the people on the boats. Last year, Coast Guardsmen seized more than 800,000 kilograms of marijuana and cocaine, and they arrested more than 700 persons trying to bring illegal drags into the United States.
    This kind of action is exciting. Most of the time, however, Coast Guardsmen say three nothing more exciting than the ocean.