According to the sociological definition of a group, one commonality the members must have is

A) commitment to group success.
B) technical background.
C) value system.
D) employment history.
E) identity and purpose.

The sociological definition of a group requires members to have identity and purpose in common. This means that they must share a sense of belonging to the group and have a common goal or reason for being part of the group. While commitment to group success, technical background, value system, and employment history may be important factors for some groups, they are not necessary for all groups according to the sociological definition.