Answer:
A makes the most sense, you would get rid of Y by multiplying it,it is the opposite of divison, this is because x is already almost by itself. the last step would be to get rid of Y. you would multiply Y to cancel it out on the right side and do the same to the left. this automatically gets rid of B and C,leaving A and D, but D doesnt have the R,so that gets rid of D, leaving A.