Choice A is the correct answer. Rewrite the equation in standard form: $3x^2 + 0x + 12 = 0$.

1. Identify $b = 0$.
2. Sum = $-b/a = -0/3 = 0$.

Note: The roots are imaginary ($2i$ and $-2i$), but their sum is still 0.

Choice B is incorrect. Choice C is incorrect. Choice D is incorrect.