Which one of the following is a homogeneous differential equation?

The real value of $m$ for which the substitution $y = u^m$ will transform the differential equation $2x^4y \frac{dy}{dx} + y^4 = 4x^6$ into a homogeneous equation is:

The general solution of the differential equation $(x \sin \frac{y}{x}) dy = (y \sin \frac{y}{x} - x) dx$ is

The probability that exactly $3$ heads appear in six tosses of an unbiased coin, given that the first three tosses resulted in $2$ or more heads is

$I: y^{\prime}=\frac{y+x}{x} ; \quad II: y^{\prime}=\frac{x^2+y}{x^3} ; \quad III: y^{\prime}=\frac{2xy}{y^2-x^2}$
$S1$: Differential equations given by $I$ and $II$ are homogeneous differential equations.
$S2$: Differential equations given by $II$ and $III$ are homogeneous differential equations.
$S3$: Differential equations given by $I$ and $III$ are homogeneous differential equations.

The general solution of the differential equation $\frac{dy}{dx} = \frac{x+y}{x-y}$ is