Find the odd number / letters / word from the given alternative:

3, 9, 6, 15
6, 18, 12, 30
4, 16, 12, 24
12, 36, 24, 60

The answer is B. 6, 18, 12, 30.

In each of the other options, the numbers are all multiples of the same number. In option A, the numbers are all multiples of 3. In option C, the numbers are all multiples of 4. In option D, the numbers are all multiples of 6.

In option B, the numbers 6 and 12 are multiples of 3, but the number 18 is not.