A Solution Of $y ^ { \prime \prime } + y = 0$

Multiple Choice

A solution of $y ^ { \prime \prime } + y = 0$ is

A) $y = \sin x + 2 \cos ^ { 2 } x$
B) $y = 2 \sin ^ { 2 } x - \cos x$
C) $y = - 2 \sin x + \cos ^ { 2 } x$
D) $y = 2 \sin x - 2 \cos ^ { 2 } x$
E) $y = 2 \sin x + \cos x$