Choice A is the correct answer. Find $a$ and $b$.

1. Find a: Y-intercept is $(0, 3)$, so $a=3$.
2. Substitute: Use $(2, 12)$ in $y = 3b^x$. $12 = 3b^2$.
3. Solve: $b^2 = 4 \implies b = 2$ (since base must be positive).
4. Equation: $y = 3(2)^x$.

💡 Strategic Tip: If given $x=2$, you need to take the square root to find $b$.

Choice B is incorrect because$3(4)^2 = 3(16) = 48 eq 12$. Choice C is incorrect because it starts at 12. Choice D is incorrect because it is linear.