Choice B is the correct answer. Always factor out the GCF first.

1. Factor out 2: $2(x^2 - 9)$.
2. Recognize that $x^2 - 9$ is a difference of squares.
3. Factor $x^2 - 9$ into $(x - 3)(x + 3)$.

Final answer: $2(x - 3)(x + 3)$.

Choice A is incorrect because $(x-3)^2$ expands to $x^2 - 6x + 9$, which has a middle term. Choice C is incorrect because while mathematically equivalent, it is not completely factored (the first factor $2x-6$ still has a GCF of 2). Choice D is incorrect because it doesn't expand to the original expression.