Which will replace the question mark (?) in the given series?
K, kl, klm, klmn, klmn...?

Given: 

K, kl, klm, klmn, klmn...?
The pattern is - 
K
KL (added 'L')
KLM (added 'M')
KLMN (added 'N')
KLMN? (Next letter should be added)
The sequence follows the alphabetical order, adding the next letter in sequence:
After N, the next letter is O.
Correct Answer: (C) O​