The formula for finding the area of a circle is pi times radius squared. Radius is half of diameter, so your radius is 3.5 ft. When you square the radius, you simply multiply it by itself, so 3.5 times 3.5, which is 12.25. you then multiply that product by pi: 3.14, which is 38.46 ft squared, but rounded up, 38.5 ft squared. So C.