Final answer:
The iron triangle is a hypothetical arrangement among three elements: an interest group, a congressional committee member or chair, and an agency within the bureaucracy.
Step-by-step explanation:
The iron triangle is a hypothetical arrangement among three elements: an interest group, a congressional committee member or chair, and an agency within the bureaucracy. Each element has a symbiotic relationship with the other two, and it is difficult for those outside the triangle to break into it. The success criteria of the iron triangle include fluid participation among interests, a great deal of competition for access to decision-makers, and a symbiotic relationship among Congressional committees, executive agencies, and interest groups. Therefore, the answer to the question is a fire station because a fire station is not an element of the iron triangle.