In recent years, temperatures in the polar areas are rising faster than anywhere else on Earth. As a result, the ice and the snow are melting at record-setting rates. One result is that sea levels are rising around the world, putting animals and people at risk. A sheet of ice acts like a huge mirror, reflecting the sun's energy. But ocean water, which is darker than ice, absorbs a lot of it. This causes the ocean to warm, which in turn speeds up ice melting and which leads to even more open waters. The cycle continues until all the ice is gone. "As the ice melts, water flows into the oceans, making them less salty. That, along with warmer water temperatures, can harm the creatures that live in, under, and near the ice," says zoologist Michael Stoddard. "Cold-adapted animals -- including polar bears, foxes, hares, and seals -- also need ice for travel and survival." "Most species of fish, sea spiders, and many other animals and plants that live in the waters of Antarctica don't live anywhere else," Stoddard says. "Many of them have special proteins in their bodies keeping them from freezing to death and have other adaptation to the cold that has yet to be explored." Therefore, experts are urging us to reconsider the way we live. The fuels that we burn in cars, power stations, and factories are largely to blame for the carbon dioxide and other greenhouse gases that are trapping overmuch heat in our atmosphere. If we can produce fewer of these gases, we can help save the polar ice. "Even small things would make a difference, if everyone did them." Michael Stoddard says, "That's what we have to figure out in the near future to help save the polar ice and thus protect the oceans and us." The passage is mainly written to   _  .
introduce the present situation of the polar areas warn people against extreme weather call on people to protect the oceans and humans advertise for volunteers to protect the environment
Question: In recent years, temperatures in the polar areas are rising faster than anywhere else on Earth. As a result, the ice and the snow are melting at record-setting rates. One result is that sea levels are rising around the world, putting animals and people at risk. A sheet of ice acts like a huge mirror, reflecting the sun's energy. But ocean water, which is darker than ice, absorbs a lot of it. This causes the ocean to warm, which in turn speeds up ice melting and which leads to even more open waters. The cycle continues until all the ice is gone. "As the ice melts, water flows into the oceans, making them less salty. That, along with warmer water temperatures, can harm the creatures that live in, under, and near the ice," says zoologist Michael Stoddard. "Cold-adapted animals -- including polar bears, foxes, hares, and seals -- also need ice for travel and survival." "Most species of fish, sea spiders, and many other animals and plants that live in the waters of Antarctica don't live anywhere else," Stoddard says. "Many of them have special proteins in their bodies keeping them from freezing to death and have other adaptation to the cold that has yet to be explored." Therefore, experts are urging us to reconsider the way we live. The fuels that we burn in cars, power stations, and factories are largely to blame for the carbon dioxide and other greenhouse gases that are trapping overmuch heat in our atmosphere. If we can produce fewer of these gases, we can help save the polar ice. "Even small things would make a difference, if everyone did them." Michael Stoddard says, "That's what we have to figure out in the near future to help save the polar ice and thus protect the oceans and us." The passage is mainly written to   _  .
A. introduce the present situation of the polar areas
B. warn people against extreme weather
C. call on people to protect the oceans and humans
D. advertise for volunteers to protect the environment
Answer: