Select the combination of letters that when sequentially placed in the blanks of the given series will complete the series.
T U P __ __ __ P K T __ __ K T U P __

T U P __ __ __ P K T __ __ K T U P __

Option a) TTUUPK

T U P T T U  P K T U P K T U P K

Option b) KTUUPK

T U P K / T U P K / T U P K / T U P K

TUPK is a repeating pattern.

Thus, the correct option is (b).