This is an example of algebraic manipulation.
We are given the formula:
A = 1/2bh
Let's see about option A.
In order to isolate b, we need to multiply both sides of the equation by 2 to get rid of the 1/2:
2A = bh
Now we can simply divide both sides by h to isolate b:
2A/h = b
Therefore, A is the correct answer.
