Choice B is the correct answer. Match parameters to $y=ab^x$.

1. Initial Value: $a = 4$.
2. Growth Factor: $b = 1.5$.
3. Combine: $y = 4(1.5)^x$.

💡 Strategic Tip:$a$ is outside, $b$ is inside the parenthesis.

Choice A is incorrect because it swaps $a$ and $b$. Choice C is incorrect because the factor is 0.5. Choice D is incorrect because it is linear.