Answer:
B. figure b.
Explanation:
Reflection symmetry refers to a symmetry with respect to an axis of reflection. Most common example is drawing an axis inside the figure, the resulting haves are like a mirror reflection.
So, in this case, if we draw a vertical axis on figure B, each half would be a reflection of each other. In other words, if we reflect figure B, it would result the same figure, because is symmetric.
Therefore, the right answer is option B.