Which of these numbers is prime?

A prime number is a natural number greater than 1 that has no positive divisors other than 1 and itself.

Let's analyze each of the given numbers:

• 9: Divisible by 1, 3, and 9 (not prime).
• 37: Divisible only by 1 and 37 (prime).
• 38: Divisible by 1, 2, 19, and 38 (not prime).
• 65: Divisible by 1, 5, 13, and 65 (not prime).
• 81: Divisible by 1, 3, 9, 27, and 81 (not prime).

From this analysis, the only number that is prime is:

B: 37.