Surface area of a sphere: S=4 Pi R^2
where R is the radius of the sphere and Pi is the constant 3.1416.
We have the Diameter D:
D=10 mi
Then we can find the radius R:
R=D/2
R=(10 mi)/2
R=5 mi
Now ww can calculate the surface area:
S=4 Pi R^2
S=4 Pi (5 mi)^2
S= 4 Pi (25 mi^2)
S= 100 Pi mi^2
This is the exact answer. Replacing Pi by 3.1416 to get an approximate answer:
S= 100 (3.1416) mi^2
S= 314.16 mi^2
Then the answer is option D. 314.16 mi^2