In the context of applying the ecological systems model, the _____ refers to those formal and informal resources and persons that the social worker needs to cooperate with to accomplish a purpose.​

A) ​target system
B) ​action system
C) ​agency system
D) ​closed system

The action system in the ecological systems model refers to the resources and individuals that the social worker must work with to achieve a goal or purpose. The target system refers to the individual or group that the social worker is trying to help, the agency system refers to the organization the social worker is affiliated with, and the closed system refers to a system that does not interact or exchange information with other systems.