Maybe we're both wrong, but I tend to agree with you 100%. It might be an error. I think it's E. Maybe someone else can shed some light as to why it's not and it's C!
After staring at it for a while, I noticed that for the 3d image from the front view, the height of the right side of the rectangle is longer in length than the left.
So it should look something like this?
It's drawn out of proportion just to make the point easier.