Use a formula to find the surface area of the square pyramid.

6ft. Slant height
3ft. Base

45 ft^2
81 ft^2
36 ft^2
72 ft^2

The formula to find the surface area of a square pyramid is:

\(Base~Area + (1/2) \times Perimeter~of~Base \times Slant~Height\)

Given:
Base = 3ft
Slant height = 6ft

First, calculate the Base Area:
\(Base~Area = (3ft)^2 = 9ft^2\)

Next, calculate the Perimeter of the base:
\(Perimeter~of~Base = 4 \times Base = 4 \times 3ft = 12ft\)

Now, plug the values into the formula:
Surface Area = 9ft^2 + (1/2) \times 12ft \times 6ft
Surface Area = 9ft^2 + (1/2) \times 72ft
Surface Area = 9ft^2 + 36ft^2
Surface Area = 45ft^2

Therefore, the surface area of the square pyramid is 45 ft^2.

So the correct answer is: 45 ft^2