The correct answer is: C. O-15, X-24.
The pattern is to add 2 to the previous number to get the next number. So, the next number after 9 is 11, and the next number after 11 is 13. However, after 13, the pattern changes to adding 3 to the previous number. So, the next number after 13 is 16, and the next number after 16 is 19. This pattern continues until the end of the sequence.
Here is a table showing the sequence:
Number | Letter ------- | -------- 3 | C 5 | E 7 | G 9 | I 11 | O 13 | K 16 | M 19 | X 22 | Y 25 | Z
Option A is incorrect because X comes before M in the alphabet.
Option B is incorrect because K comes before M in the alphabet.
Option D is incorrect because M comes before K in the alphabet.