In a rectangle we can draw two lines of symmetry:
Any rectangle has 2 lines of symmetry and it has a rotational symmetry of order 2.
Diagonals are not lines of symmetry as the opposite sides is not an exact image of each other (except for squares, in which diagonals are in fact lines of symmetry).
Answer: Rectangles (that are not squares) have only 2 lines of symmetry [Option C]