Differential Equations

Consider the differential equation $\frac{d y}{d x}=\frac{1}{a x+4 y+7}$ and the following statements

A. The given differential equation is linear in $x$.

B. The given differential equation is not linear in $y$.

C. The given differential equation is linear in $y$.

D. $e^{a x}$ is the integrating factor of the given differential equation.

Which one of the following options is true?