题目内容：
根据下面内容，回答题： Farm animals provide man with food and material for clothing, leather and other products．Some,such as horses and oxen, provide transportation and power to pull machinery．Livestock gaze on about40 percent of the United States land area．Cattle provide meat, hides and dairy products．Beef and dairy cattle account for about a third of all farm income in the U.S．Farms in the Midwest and sprawling ranches in the West raise most of the country's beef cattle．The main Dairy Belt in the U.S．extends through the Northern states from New England to Minnesota．Eastern dairy farmers in Minnesota, Wisconsin and Iowa sell most of their milk to companies that make butter, cheese and evaporated milk．Hogs grow rapidly and provide meat and materials used to make many products, Hogs thrive on corn, and farmers in the Corn Belt of the Midwest raise more than two-thirds of U．S．hogs．Sheep and goats supply man with meat, wool and skins for leather．They are hardy animals that live well on poor grazing land．Poultry includes chickens, ducks, geese, turkeys and other birds raised for meat or eggs．Many farmers keep small flocks of chickens to supply their families with eggs and meat．But．some U．S.farmers specialize in raising large flocks of meat or egg-laying chickens．They use scientific breeding and feeding methods．Some specialized farms raise mink and other animals for their fur, rabbits for meat, or silkworms for silk．Many farmers keep bees to get their honey and to help pollinate crops．
Farm animals in this passage are for________． A．farming
B．leather only
C．natural balance
D．man's need
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