One Solution of the Differential Equation $y ^ { \prime \prime } + y ^ { \prime } = 0$

Multiple Choice

One solution of the differential equation $y ^ { \prime \prime } + y ^ { \prime } = 0$ is $y = \cos x$ . A second linearly independent solution is

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