Select the letter-cluster that can replace the question mark? in the following series.PROGRESS, QTOGRESS, QTRKRESS, ?, QTRKWKZA

Select the letter-cluster that can replace the question mark? in the f

1.	Select the letter-cluster that can replace the question mark? in the following series.PROGRESS, QTOGRESS, QTRKRESS, ?, QTRKWKZA
A.	QTRKWKSS
B.	QTRKWKTY
C.	QTRKVMSS
D.	PRRKWKSS
Answer» B. QTRKWKTY