The correct statement about -9 is: It is an integer but not a whole number.
Here's the reasoning:
- Integers include all whole numbers and their negative counterparts (e.g., ..., -3, -2, -1, 0, 1, 2, 3, ...).
- Whole numbers are non-negative integers (e.g., 0, 1, 2, 3, ...).
Since -9 is negative, it is an integer but not a whole number.