The diameter is given which is 13.5feet and radius is half of diameter. Therefore radius = 6.75 feet.
Slant height = 16.8 feet
The formula of surface area of cone is

Correct option is C
Answer and Step-by-step explanation

2, -4, 6, -8, 10, -12, 14, -16
These are the next three numbers in the pattern :-12, 14, -16