Write the Product as a Sum or Difference of Trigonometric $\cos \left( - \frac { 7 \pi } { 12 } \right)$

Multiple Choice

Write the product as a sum or difference of trigonometric functions.
- $\cos \left( - \frac { 7 \pi } { 12 } \right)$

A) $\sqrt { 2 } - \sqrt { 6 }$
B) $\frac { \sqrt { 2 } - \sqrt { 6 } } { 4 }$
C) $\frac { \sqrt { 6 } - \sqrt { 2 } } { 4 }$
D) $\sqrt { 6 } + \sqrt { 2 }$