What we want to get is $\frac{\frac{a + \frac{b}{c}}{\frac{d}{e}}}{2}$. This has to be achieved by doubling one of the variables. This means that we have to double a variable so that the 2 becomes the denominator of our expression. The only way to obtain it is to double D, so that, since it is a fraction at the denominator, it is as we were multiplying for the reciprocal of the fraction. Then, answer B!