Find Dy/dt $$y = \cos ( \sqrt { 6 t + 12 } )$$

Multiple Choice

Find dy/dt.
- $$y = \cos ( \sqrt { 6 t + 12 } )$$

A) $- \frac { 1 } { 2 \sqrt { 6 t + 12 } } \sin ( \sqrt { 6 t + 12 } )$
B) $- \sin \left( \frac { 3 } { \sqrt { 6 t + 12 } } \right)$
C) $- \sin ( \sqrt { 6 t + 12 } )$
D) $\frac { 3 } { \sqrt { 6 t + 12 } } \sin ( \sqrt { 6 t + 12 } )$