To solve this problem, we need to identify the letter sequence pattern and fill in the blanks with the correct sequence from the given options. Let's break down the sequence provided:

The incomplete sequence is: M N _ O J K M _ Q O J K _ N Q _ J K M N Q O _ K M N

First, observe the initial set of letters:

• M N _ O J K

The pattern seems to be a repeat cycle of six letters with blanks that need to be filled sequentially.

Next, replicate the identified initial sequence pattern:

• M N Q O J K

After filling in the blanks as per this sequence into the original series, we get:

• M N Q O J K
• M N Q O J K
• M N Q O J K

Notice the individual sections continue to maintain this consistent pattern. So, the blanks should filled as:

• First blank: Q
• Second blank: N
• Third blank: M
• Fourth blank: O
• Fifth blank: J

The completed pattern will be: M N Q O J K M N Q O J K M N Q O J K M N Q O J K M N

This matches the sequence 'QNMOJ'. Hence, the option that completes the sequence is:

Correct Answer: QNMOJ

In conclusion, meticulous observation of the pattern repetition led to the correct choice.