10/40. First, I simplified all of the given rations. You do this by finding the two numbers greatest common factor. For example, 3/12, 3 goes into 3 once and 3 goes into 12 four times. So that ratio would be 1/4. If you continue the pattern you would get 1/4 for all of them. Therefore, 10/40 would be correct since it's ratio would also be 1/4.