first pick a number, any random number ill just use 1 cause its simple to multiply.
1 x 1/3 = 1/3 / 4/9 = 1/3 x 9/4 = 9/12 or 3/4
now take the number 1 and do to it what a, b and c tells you to and see which one gives you the same answer of 3/4.
A.) 1 x 3/4 = 3/4 (this one seems to be correct)
B.) 1 x 4/3 = 4/3 (this is not correct)
c.) 1/ 2/5 = 1x 5/2 = 5/2 (this is not correct either)
A is your answer.