Answer: Choice A
We have the fractions (2x-1)/(x+2) and 7/(x^2-12) being divided. When you divide two fractions, you flip the second one and multiply.
The general template is: P/Q divided by R/S = P/Q times S/R
So we'll flip the fraction 7/(x^2-12) to get (x^2-12)/7 then multiply straight across to end up with what choice A is showing on the right hand side.