Environment-conscious members of an organization have taken up an initiative to reduce the number of styrofoam cups and sheets of paper used by the company. they organize meetings by themselves on a weekly basis where they discuss methods of making their company more eco-friendly. the members, in this case, constitute a(n

An appropriate answer could be an interest groups. These are groups that are formed to influence government policy on specific topics. Interest groups influence policies by creating petitions, lobbying or hiring lobbyists, advertising in the media or endorsing other groups that support their cause. Interest groups are usually non-profit organizations and can be composed entirely of volunteers. 

Ad hoc committee in other words a committee which sprung up spontanteously from the concerns of the employees as opposed to one organized by the employer.

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