The Differential Equation $x y d x + \left( x ^ { 2 } + y ^ { 2 } \right) d y = 0$

Multiple Choice

The differential equation $x y d x + \left( x ^ { 2 } + y ^ { 2 } \right) d y = 0$ is

A) exact with solution $x ^ { 2 } y / 2 + y ^ { 3 } / 3 = c$
B) exact with solution $x ^ { 2 } y / 2 + y ^ { 2 } / 2 = c$
C) exact with solution $x ^ { 2 } y / 2 + y ^ { 3 } / 3 + c$
D) not exact but having an integrating factor x
E) not exact but having an integrating factor y