Which of the Following Functions Are Solutions to the Differential $\frac { d y } { d x } = - \frac { 1 } { 6 } y$

Multiple Choice

Which of the following functions are solutions to the differential equation $\frac { d y } { d x } = - \frac { 1 } { 6 } y$ ? (Mark all correct answers.)

A) $y = \sin ( 6 x ) + \cos ( 6 x )$
B) $y = 6 \cos x - \sin x$
C) $y = e ^ { x / 6 }$
D) $y = e ^ { - x / 6 }$