Convert the Degree Measure to Radians $\pi .$ - $810 ^ { \circ }$

Convert the degree measure to radians. Leave answer as a multiple of $\pi .$
- $810 ^ { \circ }$

A) $- \frac { 9 \pi } { 2 }$

B) $- \frac { 9 \pi } { 4 }$

C) $\frac { 9 \pi } { 2 }$

D) $9 \pi$