The answer is B. 90 cm. This is because you can find surface area by adding the areas of each face together. The square face has an area of 9, and then you multiply that by 2 since there are two squares of the same side lengths. Next, you find the area of the rectangle, which is 18. Since there are 4 rectangles with equal side lengths, you would multiply 18 by 4. Add the two sums 18 and 72, and you get an answer of 90 cm. Hope this helps!