The area of a circle is found using the formula A = PI x r^2
r is the radius, which is half the diameter.
r = 12 / 2 = 6
Area of full circle = 3.14 x 6^2 = 113.04 square units.
There are 8 equal sectors ( they are all 45 degrees), so divide the total area by 8.
113.04 / 8 = 14.13 square units, rounded to the nearest tenth = 14.1 square units.
The answer is D.