Answer: B. Two or more individuals who share a set of norms, values or belief and have a certain implicitly or explicitly defined relationships to one another such that their behavior is interdependent.
Explanation: A group is simply composed of more than one person, and as such members of a group have something in common, it could be a behavior, attitude, like or anything which is common to all members of the group. A group usually possess a relationship pattern which may be lucid or very obvious and sometimes may not be known to others people outside their group that is they exhibit a a sort of positive correlation and as such members of the group exhibit a mutual dependence on one another.