阅读短文，从下面每小题的A、B、C、D四个选项中选出最佳选项。
People in Western countries are eating less meat these days, whether for their health or because they want to protect animals. But now they have another reason.
Eating less meat can help to prevent climate change, according to a recent study published in Nature.
Raising livestock (家畜) is bad for the environment. When animals like cows digest (消化) food, their stomachs make greenhouse gases, which are a major cause of global warming. Seventeen percent of greenhouse gas emissions (排放) come from livestock farming, The New York Times reported.
In addition, to raise these livestock, people have to cut down forests and turn them into farms. Forests play a key role in fighting global warming because they absorb greenhouse gases.
Eating less meat according to certain guidelines could cut global food-related emissions by nearly a third by 2050, the study found. Maintaining (保持) a vegetarian diet in the long term could bring down emissions by 63 percent.
But eating less meat won't be easy. According to the study, people in Western countries will need to eat 90 percent less meat than they do now in order to have an impact (影响) on our climate. Scientists are now trying to find new foods to replace meat.
Some say that insects (昆虫) could help. A 2013 UN report said that eating insects is healthier and better for the environment. They produce 75 percent less greenhouse gases than livestock.
Some experts are creating lab-grown meat. They make meat in a lab using livestock cells (细胞). In March, US company JUST said people in the US might be able to buy its lab-grown meat by the end of this year.
