Final answer:
Supervisors are not considered part of bargaining units because they have managerial roles that conflict with the collective interests represented by labor unions.
Step-by-step explanation:
The group that is not considered "employees" and may not be in any bargaining unit is e. supervisors. Supervisors often have managerial roles and responsibilities that include overseeing employees, which disqualifies them from being part of bargaining units typically represented by labor unions.
Labor unions advocate for the rights and benefits of workers, dealing with issues such as wages, working conditions, and health insurance. Supervisors may have a role in negotiations or disciplinary actions on behalf of the employer, which conflicts with the collective interests represented by unions.