I'll use approximate figures. Earth is about 8,000 miles in diameter so the scale is 8000 mi / inch. Neptune is about 3 billion miles from the sun. Divide 3,000,000,000 by 8,000 to get how many inches to place Neptune on the model. 375,000 inches is about 9600 meters (because there are about 39 inches per meter). The closest answer to 9600 meters (9.6 kilometers) is C.