Answer:
B. 140.4 square feet.
Explanation:
If all faces are equilateral, and they are all congruent, that means the surface area of the pyramid is formed by 4 equal triangles, including the base.
We just need to find the area of one triangle and then multiply it by 4.
According to the image, the height of a triangle face is
, and its base is
. So, the area is


Then, the total surface area of the pyramid is

Therefore, the right answer is B. 140.4 square feet.