Be quick: i'm terrible at math, but my god someone , this is my last try on this assignment, and trust me all the points i can get, plus if you don't mind giving a slight explanation so i can learn how to do this myself as well.

For prisms, use the formula: 2B + Ph

B = base of figure, here it is the trapezoid.
The area of the trapezoid is (3+6)*4/2 = 18

P = perimeter of the base, which is 3+4+5+6 = 18
h = height, here it is 5.

Thus the answer is:
2*18 + 18*5 = 36 + 90 = 126 cm^2
(C)