Answer: Line B
Step-by-step explanation:
A line of symmetry cuts through a shape, leaving equal area halves on each side, exactly identical.
Line A does not cut through the shape.
Line D cuts through, but the shapes are not equal area nor are they identical.
Line C comes close but even it does not have equal area halves, and the two halves are different.
Line B cuts evenly down the middle, with equal, identical halves.