Find the Exact Value of the Expression $$\cos ^ { - 1 } \left[ \cos \left( \frac { \pi } { 10 } \right) \right]$$

Multiple Choice

Find the exact value of the expression. Do not use a calculator.
- $$\cos ^ { - 1 } \left[ \cos \left( \frac { \pi } { 10 } \right) \right]$$

A) $\frac { \pi } { 10 }$
B) $10 \pi$
C) $- 10 \pi$
D) $- \frac { \pi } { 10 }$