Explanation:
When given a formula, and we know the values of the variables plug in the number and units
So,
Instead of Saying

We know
B= 15 in^2
h=28 in

We know that

So

And ofc,

So we get

So the correct answer is the fourth option.
This is a skill. you must master at Algebra and please remember this:
IF YOU ARE GIVEN A FORMULA AND YOU KNOW THE VALUE OF SOME VARIABLE IN THE FORMULA, SUBSITUTE THE VARIABLE FOR THE VALUE