Can someone please explain how the answer in PT 15 S2 Q08 in logical reasoning is answer A and not C? I'm confused on this one.

Admin note: Edited title. Please use the format "PT#.S#.Q# - [brief description of the question]"

I was doing well on practice LSATs and was scoring in the mid 150's (couple weeks ago I got a 155) until I took a recent practice LSAT and scored a 145. My blind reviews at at a consistent 165 so I know what I am doing but I'm not sure what went wrong with this recent LSAT. Does anyone have any study advice on concerning a large score drop?