Select the letter - cluster that can replace the question mark (?) in the following series.SGTA, UGVA, WGXA, ?, AGBA

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

1.	Select the letter - cluster that can replace the question mark (?) in the following series.SGTA, UGVA, WGXA, ?, AGBA
A.	ZGZA
B.	YGZA
C.	ZGAA
D.	YGAA
Answer» C. ZGAA