Answer
The graph is symmetric with respect to the line $\theta =\frac{\pi }{2}$.
Work Step by Step
We look for symmetry by making the following substitutions:
(a) $\theta \to - \theta$ :$$r\sin (- \theta )=2 \quad \Rightarrow \quad r\sin \theta =-2$$Thus, the graph does not necessarily have symmetry with respect to the polar axis.
(b) $r \to -r, \quad \theta \to -\theta$ :$$(-r)\sin (-\theta ) =2 \quad \Rightarrow \quad r\sin \theta =2$$Thus, the graph is symmetric with respect to the line $\theta=\frac{\pi}{2}$.
(c) $r \to -r$ :$$(-r)\sin \theta =2 \quad \Rightarrow \quad r\sin \theta =-2$$Thus, the graph does not necessarily have symmetry with respect to the pole.
