Which groups do you need to assign to an OS user to enable that user to connect as “/ as sysdba”?

You have the following operating system (OS) groups:
1)dba This is the OSDBA group.
2)oper This is the OSOPER group.
3)oinstall This is the owner of Oracle software.
Which groups do you need to assign to an OS user to enable that user to connect as "/ as sysdba"?

A.
Only 1

B.
1, 2, and 3

C.
1 and 2; 3 not required

D.
2 and 3; 1 not required

E.
1 and 3; 2 not required