Use a Sum or Difference Identity to Find the Exact $$\frac { \tan 100 ^ { \circ } - \tan ( - 20 ) ^ { \circ } } { 1 + \tan 100 ^ { \circ } \tan ( - 20 ) ^ { \circ } }$$

Multiple Choice

Use a sum or difference identity to find the exact value.
- $$\frac { \tan 100 ^ { \circ } - \tan ( - 20 ) ^ { \circ } } { 1 + \tan 100 ^ { \circ } \tan ( - 20 ) ^ { \circ } }$$

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