A., because to find LCD, you must find the LCM of the three denominators. In this case, one of the denominators has the answer, which is 16, because 2, 8, and obviously 16 all go into 16.
You then have to also multiply the numerators by the same number that you are multiplying the denominators by. 2 x X = 16 -> X = 8, so you multiply 1 x 8 and get 8, so the first fraction is 8/16. 16 x X = 16 -> x = 1, 3 x 1 = 3, so the next one remains 3/16. 8 x X = 16 -> X = 2, 2 x 7 = 14, so the last one is 14/16.