Mary pulled out the "Dog" vial, then after some thought, the "Human" vial, but after looking at the vials a second, she hesitated.
"Even if I don't take the whole thing, I don't really know how much a little bit will change me...if I try 'Dog,' what if I change too much? I won't be able to open the human vial with paws!" she pondered. Finally, sighing, she put the "Dog" vial back in its place, but placed the "Human" vial on the table. She considered just trying one of the human characteristic vials, but those seemed rather tame. If she was going to do this, she wanted the change to be worth the trouble.
In the end, Mary decided she wanted to try something that definitely wouldn't affect her ability to open the other vials; preferably something with hands, or at least hand-like paws. She began looking through the various options.
"Dragon...too big, no way I could do that in here....Centaur, looks like...tempting, but I'd probably still be stuck inside, I couldn't go stomping around the hallways like that...birds are pretty good with their beaks and claws, but I don't want to risk it, not yet at least..."
Finally, she narrowed it down to a few choices, and decided which one to take.