Answer: A--- Community of Interest
Step-by-step explanation:
A community of interest is a community of people sharing similar demands or interest through the exchange and interaction of ideas, thoughts, knowledge, information, or data. about the common interest in order to develop coordination and collaboration among the people involved to solve the common goal.
The NLRB in including the clerical and factory workers in the same bargaining unit because they have indicated that their demands are very similar is applying a principle of Community of interests.