The answer is (c): the image in the mirror is inverted front-to-back, but that doesn't much matter because it does not have any depth. It is not inverted either top-to-bottom or right-to-left, so the lettering in both the object and the image goes from the left side of the cars to the right side. When you turn around the lettering on the van goes from right to left, as seen in the center photograph!
This is the same problem discussed in Question #19 (photograph at the right above). If you were to place your head between the transparency and the mirror of Question #19, you would need to turn your head around in order to see the actual transparency, the same thing that happens when you turn around to view the lettering on the van directly.
