11, 13, 17, 19, 23, 25, ?

The answer is $\boxed{\text{29}}$.

The sequence is a list of prime numbers, which are numbers that are only divisible by themselves and 1. The next prime number after 25 is 29.

Option A, 26, is not a prime number because it is divisible by 2.

Option B, 27, is not a prime number because it is divisible by 3.

Option C, 29, is a prime number, so it is the correct answer.

Option D, 37, is a prime number, but it is not the next prime number after 25.