Solve the Problem $f ( \theta ) = \sin \theta$ And $f ( a ) = - \frac { 1 } { 6 }$

Multiple Choice

Solve the problem.
-If $f ( \theta ) = \sin \theta$ and $f ( a ) = - \frac { 1 } { 6 }$ , find the exact value of $f ( a ) + f ( a + 2 \pi ) + f ( a + 4 \pi )$ .

A) $- \frac { 1 } { 2 }$
B) $- \frac { 1 } { 2 } + 6 \pi$
C) $- \frac { 1 } { 6 }$
D) $\frac { 3 } { 2 }$