1. The problem asks us to identify which numbers among 15, 13, 9, and 8 are prime. 2. A prime number is a natural number greater than 1 that has no positive divisors other than 1 and itself. 3. Check each number: - 15: Divisible by 1, 3, 5, 15 (not prime) - 13: Divisible only by 1 and 13 (prime) - 9: Divisible by 1, 3, 9 (not prime) - 8: Divisible by 1, 2, 4, 8 (not prime) 4. Therefore, the only prime number in the list is 13.