The particular integral of the differential equation $f(D)y=e^{ax}$ where $\;.f(D)=(D-a)g(D).g(a)\neq 0$ is

Question

\[\begin{array}{1 1}(1)me^{ax}&(2)\frac{e^{ax}}{g(a)}\\(3)g(a)e^{ax}&(4)\frac{xe^{ax}}{g(a)}\end{array}\]