The answer choice below (or above) me is correct I beleive I just wanted to show proof.
15 ÷ 249 = 0.06024096
20 ÷ 332 = 0.06024096
As you can see both numbers are equal and if you round it the unit rate will be 0.06¢ (maybe im not sure if you'll have to change the 15 since we moved the decimal in 2.49)