Final answer:
A whole number less than 100 can either be a 1-digit number or a 2-digit number, depending on whether it is less than 10 or between 10 and 99, respectively.
Step-by-step explanation:
A whole number less than 100 is a 2-digit number. This is because a 2-digit number has two digits, and the maximum value a digit can have is 9. So, the largest 2-digit number is 99, which is less than 100.
If a whole number is less than 100, then it is either a 1-digit number or a 2-digit number. Whole numbers less than 10 are considered 1-digit numbers, whereas whole numbers from 10 up to 99 are considered 2-digit numbers. Therefore, the correct answer to the question whether a whole number less than 100 is a 2-digit number, 1-digit number, prime number, or odd number, is that it can be either a) a 2-digit number or b) a 1-digit number.