The solution of the differential equation $\large\frac{dy}{dx}=\frac{y}{x}+\frac{\phi (y/x)}{\phi ' (y/x)}$ is

Question

\[\begin {array} {1 1} (a)\;x \phi \bigg(\frac{y}{x}\bigg)=k & \quad (b)\;\phi \bigg(\frac{y}{x}\bigg)=kx \\ (c)\;y \phi \bigg(\frac{y}{x}\bigg)=k & \quad (d)\; \phi \bigg(\frac{y}{x}\bigg)=ky \end {array}\]