Write a multi-choice question for the following article, with the given choices and answer: Article: Scientists are learning new things about Antarctica, the coldest place on Earth. For example, the Antarctic ice sheet is shrinking. A new study found that summer ice loss in parts of Antarctica was at its highest level in 1,000 years. The study showed that Antarctic ice was melting mostly from below ice shelves, where the water is warmer than the ice. Eric Rignot is an earth system expert at the University of California, Irvine. He also works for the American space agency, NASA. There he serves as senior research scientist at NASA's Jet Propulsion Laboratory, also in California. He says ice melting from below is responsible for 55 percent of the shelf loss from 2003 to 2008. That is a much higher rate than scientists thought earlier. Professor Rignot and his team used satellite observations, radar and computer models to measure features above the ice to learn what was going on below. The measurements show differences from one area to the next around the continent. The major ice shelves are called Ross, Filchner and Ronne. They make up two-thirds of Antarctica's ice shelves. But they are responsible for only 15 percent of the melting ice. The professor says even small changes, like changes in ocean flow driven by wind, can make a huge difference in the melting of the ice shelf. Sixty percent of the Earth's fresh water is held in the huge Antarctic ice sheet. Professor Rignot says the study will help experts predict how the continent reacts to warmer ocean waters and helps to cause rising sea levels around the world. The study was published in the journal Science. Options: A He serves as senior research scientist at NASA's Jet Propulsion Laboratory. B They used satellite observations, radar and computer models to know the things happening below the ice. C Small changes, like changes in ocean flow driven by wind, can make a huge difference in the melting of the ice shelf. D They melted 55% of the Antarctica's ice to prove their theory is right. Answer: B They used satellite observations, radar and computer models to know the things happening below the ice. Question:
Answer:
How did Eric Rignot and his team do the research?