Which sentence in the passage best conveys that vegetarianism is good for the environment? Why Go Vegetarian?

People choose to eliminate meat from their diets for many reasons. Concerns about health risks, farming practices, and environmental problems are just a few.
In recent years, many animal rights activists have investigated the way animals are treated on large factory farms. They found that many farm animals spend their entire lives in cages where they are often neglected and abused. Investigators also found that these animals are often fed chemicals in order to fatten them up or to make them produce more milk or eggs.
Some health experts say that a healthy vegetarian diet can help reduce heart disease, cancer, and stroke. They say vegetarians also have lower cholesterol and blood pressure and are less likely to develop diabetes. Others claim that a vegetarian diet will lead to a longer life. Much of the evidence to support these claims comes from scientific studies.
Many vegetarian supporters would say the best thing you can do for the environment is to stop eating meat. Some estimates show that the amount of water used just for farming equals the amount of water used for everything else in the United States combined. Supporters say it takes 2,500 gallons of water to produce a single pound of beef. This is equivalent to taking a long shower every day for two-and-a-half weeks. The fertilizer used to grow crops that feed animals has also been identified by the Environmental Protection Agency as a major water pollutant.
However, there are many who disagree with vegetarian supporters. A recent United Kingdom study shows that while vegetarians seemed less likely to have cancer overall, they were more likely to have colon cancer. Another study says that vegetarians risk not having enough iron because the richest sources of iron come from meat. Some experts even say that animal fats are "necessary for human health."
Organizations such as The Heartland Institute, a Chicago-based research center, deny that meat production harms the environment. In fact, they say that most of the land that is used for livestock farming is not suitable for growing food. So using it to raise cattle doubles the amount of food produced. Heartland also says that safe practices are required by law and that farmers must take care of their animals in order to make money. They say that poorly fed and treated animals produce less meat. In turn, farmers make less money.
No matter which side you agree with, you should always consult with your doctor before changing your diet.