Select the combination of letters that when sequentially placed from left to right in the blanks of the given series will complete the letter series.P Q _ _ T _ _ R S T P _ R _ T _ Q _ S T

Let's find the total length of the sequence, including the blanks. There are 20 spaces in total. Let's try dividing it into groups of 5 letters each:P Q _ _ T | _ _ R S T | P _ R _ T | _ Q _ S TBy comparing the repeating segments across groups:The general structure of the repeating pattern is P Q R S T.Let's substitute letters to complete each block according to P Q R S T:First block: P Q [R] [S] TSecond block: [P] [Q] R S TThird block: P [Q] R [S] TFourth block: [P] Q [R] S TCollecting the sequentially inserted letters from left to right:S, R, P, Q, Q, S, P, RThis matches Option B.