Choice A is the correct answer. Square root property.

1. Logic: Numbers whose square is less than 9 are between -3 and 3 (e.g., 0, 2, -2).
2. Algebra: $|x| < 3 \rightarrow -3 < x < 3$

?�� Strategic Tip:$x^2 < a^2$ is equivalent to $-a < x < a$.

Choice B is incorrect because it includes large negative numbers (e.g., -10) whose square is $>9$. Choice C is incorrect because it describes $x^2 > 9$. Choice D is incorrect because it misses negative solutions.