Select the combination of letters that when sequentially placed in the blanks of the given series, will logically complete the series.

_ T W R U _ S N Q L _ J M H K _ I D G _​​

Given: _ T W R U _ S N Q L _ J M H K _ I D G _

Now, we check each options.

Option (a): YQOEB (Not Follow)

Y T / W R / U Q / S N / Q L / O J / M H / K E / I D / G B

Option (b): ZQNEC (Not Follow)​

Z T / W R / U Q / S N / Q L / N J / M H / K E / I D / G C

Option (c): ZPNFC (Not Follow)​

Z T / W R / U P / S N / Q L / N J / M H / K F / I D / G C

Option (d): YPOFB (Follow)​

Y T / W R / U P / S N / Q L / O J / M H / K F / I D / G B

So, the pattern is (- 5) between two letters. 

Thus, correct option is (d).