Both A and C are the same shape, same size, but C is flipped over. If you were to cut out the two shapes and put them over one another, they would be the same. You can also count the blocks that are in the shape itself to see if they match.
The longer side on both has 2.5 blocks in it, the side is two blocks tall, and the smaller line has 1.5 of the block shown.
I'll will implement a sketch to show you what I mean and submit it here. Look at it if you are still confused