$\begin{array}{1 1} (A) \;0^{\large\circ}\; or \;180^{\large\circ} \\ (B) \;90^{\large\circ}\;or \;270^{\large\circ} \\ (C)\; 60^{\large\circ}\; or \;120^{\large\circ} \\ (D)\; 30^{\large\circ}\; or \;150^{\large\circ} \end{array} $