PLZ I NEED HELP I DON'T UNDERSTAND

I believe the answer is C, 105sq cm.
To find the surface area of the pyramid u need to find the area of all the faces and combine them. So 1/2•5•8=20, and there are four triangular faces with the same measures so u could do 20•4= 80. Then since it’s a square pyramid, the side lengths on the square are all five so do 5•5=25. Finally you add the 80 and the 25 to get 105 sq cm.

Hope this helped!

The answer is, the streetlight is 18 inches tall.