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

ROM, URJ, XUG, AXD, ?

Which letter cluster will replace the question mark (?) to complete the given series?
 ETRE, AZJG, WFBI, SLTK, ?

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

REV, UXD, XQL, AJT, ?

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, ?

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

TTDS, VMLP, XFTM, ZYBJ, ?

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

AVTE CTRG ERPI GPNK   ?

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

TYG, ?, PSM, NPP, LMS

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

RMTS, WGAK, BAHC, GUOU, ?