Which of the following are first order linear differential equations?

A. $\frac{dy}{dx} = y^2-3y$

B. $\left(\frac{dy}{dx}\right)^2+\cos(x)y=5$

C. $\frac{dP}{dt}+2tP = P + 4t -2$

D. $\sin(x)\frac{dy}{dx} - 3y = 0$

E. $x\frac{dy}{dx} - 4y = x^6e^x$

F. $\frac{d^2y}{dx^2} + \sin(x)\frac{dy}{dx}=\cos(x)$