A : B :: C : ? Which answer figure fits in place of the question mark?

B is the reflection of A in a flat (horizontal) mirror line: top and bottom change places but left and right stay. Reflecting C this way makes the flag hang downwards with its cloth still on the right, and the dot moves to the bottom-left: (c). (b) is a half turn, which puts the cloth on the left, and (a) mirrors left-right.