Find the missing letter cluster in the given series:

BYHN, CWKM, EUNL, _______ LQTJ

The logic followed here is: 

• First letter → Increasing number series is added to the position value according to the English alphabetic series.
• Second letter → (2) is subtracted from the position value according to the English alphabetic series.
• Third letter → (3) is added to the position value according to the English alphabetic series.
• Fourth letter → (1) is subtracted from the position value according to the English alphabetic series.

So,

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Hence, "Option - (1)" is the correct answer.