Choice B is the correct answer. This equation can be solved by factoring out the Greatest Common Factor (GCF).

1. Identify the GCF of $x^2$ and $-4x$, which is $x$.
2. Factor out $x$: $x(x - 4) = 0$.
3. Set each factor to zero: $x = 0$ or $x - 4 = 0$.
4. Solve: $x = 0$ or $x = 4$.

Choice A is incorrect because it misses the solution $x=0$. Dividing both sides by $x$ is invalid because $x$ could be zero. Choice C is incorrect because $x-4=0$ gives $x=4$, not -4. Choice D is incorrect because this would be the solution for $x^2 - 4 = 0$ (Difference of Squares).