Write the Product as a Sum or Difference of Trigonometric $\sin 15 ^ { \circ } \cos 105 ^ { \circ } + \cos 15 ^ { \circ } \sin 105 ^ { \circ }$

Multiple Choice

Write the product as a sum or difference of trigonometric functions.
- $\sin 15 ^ { \circ } \cos 105 ^ { \circ } + \cos 15 ^ { \circ } \sin 105 ^ { \circ }$

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