Find the area of the circle. leave your answer in terms of pi.

the diameter of the circle is 14 so i know the radius is 7.

i think i have to do this:

3.14 * 7

but i'm not sure if that's right but if it is i'm not sure what to do after.

so the answer choices are:

a: 7 pi square feet
b: 14 pi square feet
c: 28 pi square feet
d: 49 pi square feet

? ?