Which letter-cluster will replace the question mark (?) to complete the given series?

LMR, PUA, TCJ, XKS, ?

Which letter-cluster will replace the question mark (?) to complete the given series?

ABCD, FVJV, KPQN, PJXF, ?

Which letter-cluster will replace the question mark (?) to complete the given series?

QRM, PWD, OBU, NGL, ?

Which letter-cluster will replace the question mark (?) to complete the given series?

QML, PRC, OWT, NBK, ?

A series is given with one term missing. Select the correct alternative from the given ones that will complete the series.
 NMQR, NQYD, NUGP, NYOB, ?

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

ROM, URJ, XUG, AXD, ?

Select the combination of letters that when sequentially placed in the blanks of the given series will complete the series.
 A B Z _ P A B _ K P A B X K _ A B _ K P

Which letter-cluster will replace the question mark (?) to complete the given series?
 ZFOE, PYUA, FRAW, VKES, ?