Choice A is the correct answer. Use the points to find $a$ and $b$.

1. Find a: The y-intercept is $(0, 10)$, so $a = 10$.
2. Find b: The function passes through $(1, 20)$. Substitute into $y = 10b^x$: $20 = 10b^1$.
3. Solve: $20 = 10b \implies b = 2$.
4. Equation: $y = 10(2)^x$.

💡 Strategic Tip: The point $(1, y)$ tells you the value of $a \times b$. Divide by $a$ to get $b$.

Choice B is incorrect because it represents decay. Choice C is incorrect because it is a linear function. Choice D is incorrect because it swaps the initial value and the base.