Select the letter-cluster from among the given options that can replace the question mark (?) in the following series. RN, NP, JR, ?, BV

ER ET FS FT

FT

Explanation: RN, NP, JR, ?, BV The logic followed here is : R → (-4) → N → (-4) → J → (-4) → F → (-4) → B   N → (+2) → P → (+2) → R → (+2) → T → (+2) → V   So, the letter-cluster that replaces the (?) to complete the series is "FT"