An Integrating Factor for the Linear Differential Equation $y ^ { \prime } + y / x = x$

Multiple Choice

An integrating factor for the linear differential equation $y ^ { \prime } + y / x = x$ is

A) $1 / x$
B) $x$
C) $1 / x ^ { 2 }$
D) $x ^ { 2 }$
E) $e ^ { - x }$