#### Answer

The graph is symmetric with respect to the polar axis. It may or may not have other symmetries.

#### Work Step by Step

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