Use a Sum or Difference Identity to Find the Exact $\sin 255 ^ { \circ } \cos 15 ^ { \circ } - \cos 255 ^ { \circ } \sin 15 ^ { \circ }$

Multiple Choice

Use a sum or difference identity to find the exact value.
- $\sin 255 ^ { \circ } \cos 15 ^ { \circ } - \cos 255 ^ { \circ } \sin 15 ^ { \circ }$

A) $\frac { \sqrt { 3 } } { 2 }$
B) $- \frac { 1 } { 2 }$
C) $- \frac { 17 } { 4 }$
D) $- \frac { \sqrt { 3 } } { 2 }$