No need to guess! You're right, A and C are closest - (A-C) shows fewer differences than (B-C). Here are the diffs for the images (with C-C as a sanity check):

No need to guess! You're right, A and C are closest - (A-C) shows fewer differences than (B-C). Here are the diffs for the images (with C-C as a sanity check): http://i.imgur.com/GQGLE61.jpg http://i.imgur.com/GQGLE61.jpg As other commenters have said, C is just the highlight-free version of A, which the diffs fairly clearly show. EDIT: For reference, here's A-B. http://i.imgur.com/DW8TL7A.jpg http://i.imgur.com/DW8TL7A.jpg