The correct option is D HL
Each pair of letters AM, BN, CO and DP has 12 letters in between them.
Now, the pair of letters EI, FJ and GK each has 3 letters in between them.
Also, the first letter of each pair of alphabets at odd position are consecutive and same with the pair of letters at even position.
Clearly, HL will fill the blank.
Hence, option (D) is the correct answer.