Hey there mate!
Please check the attached answer of picture for explanation.

It’s gonna be B coefficient
The diameter is 18.8 feet
I believe the circumference is 59.0 feet
Given is triangle with base = 10 cm and perpendicular height = 3 cm.
We know the formula for area of triangle is given by :-
Area =
× (Base) × (perpendicular height)
Area =
× (10) × (3)
Area = 
Area = 15 cm²
So, final answer is 15 cm².