The answer is d.42 because since the denominator(8) is being multiply by 6 to get 48, you should multiply 7 by 6 too to get the answer 42. And so the answer is 42/48.
A=pi(c/2)^4=pi^2/c^216=(5pi)^2/8=25pi^2/8

Use the formula above to find the surface area of a cylinder.
For the given cylinder the given data is the height (6mi) and diameter (16mi), use the diameter to find the radius:

Surface area:

Then, the surface area of the given cylinder is: 224π square miles
Its 1/7 because parallel lines have the same slope