Use a Sum or Difference Identity to Find the Exact $\tan \left( - 15 ^ { \circ } \right)$

Multiple Choice

Use a sum or difference identity to find the exact value.
- $\tan \left( - 15 ^ { \circ } \right)$

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