We have 8 sides to calculate, it will be hard to explain which side I'm calculating without marking on the picture.
We will start with the front facing side. We can break this up into an 8ft x 8ft square, and a 14ft x 6ft rectangle. The area equals:
8ft x 8ft + 14ft x 6ft = 148ft^2
The front facing is the same area as is back facing counterpart so we can multiply the surface area by 2:
148ft^2 x 2 = 296f^2
Adding the bottom surface area 6ft x 14ft:
6ft x 14ft + 296ft^2 = 380ft^2
Adding the right side 6ft x 14ft:
6ft x 14ft + 380ft^2 = 464ft^2
Adding the left side 8ft x 6ft:
8ft x 6ft + 464ft^2 = 512ft^2
Adding the 3 sides on the top 8ft x 6ft (top facing), 6ft x 6ft (top facing), and 6ft x 6ft (left facing):
8ft x 6ft + 512ft^2 = 560ft^2
6ft x 6ft + 560ft^2 = 596ft^2
6ft x 6ft + 596ft^2 = 632ft^2
Therefore the answer is C, 632 ft^2.