Find the Exact Value of the Expression $\sec 240 ^ { \circ }$

Multiple Choice

Find the exact value of the expression.
- $\sec 240 ^ { \circ }$

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