The figure has reflective symmetry about a line if that line divides the figure in two similar parts, which are reflections of one another.
Notice that the two figures formed when the shape is divided by line k are not similar, since one has 7 vertices and the other just 4.
Notice that the two figures formed when the shape is divided by line m are not similar, since one has 7 vertices and the other just 4.
The line l divides the figure in two shape, one is a trapezoid and the other isn't.
Only line n divides the figure in two similar shapes.
Therefore, the correct choice is B) n only.
