Which of the Following Is an Exact Differential Equation?
$x y ^ { 4 } d x + 2 x ^ { 2 } y ^ { 3 } d y$

Multiple Choice

Which of the following is an exact differential equation?

A) $x y ^ { 4 } d x + 2 x ^ { 2 } y ^ { 3 } d y$
B) $x ^ { 3 } y ^ { 4 } d x + 2 x ^ { 2 } y ^ { 3 } d y$
C) $x y ^ { 4 } d x + 2 x ^ { 4 } y ^ { 3 } d y$
D) $x y ^ { 4 } d x + 2 x y d y$
E) $x y d x + 2 x ^ { 2 } y ^ { 3 } d y$