Which of the following is the odd one out?

To find the odd one out, we must analyze the mathematical properties of the numbers in each option. Options A, B, and D all consist exclusively of prime numbers.
Option A (2, 3, 5) contains the first three primes.
Option B (11, 13, 17) lists consecutive prime numbers greater than 10.
Option D (7, 19, 23) also comprises prime numbers.
In contrast, Option C (4, 6, 8) consists entirely of even composite numbers. Since the other three groups share the common characteristic of being prime, Option C is the distinct set because it contains even numbers that are not prime. Therefore, Option C is the correct answer.