What is the primary purpose of special-interest groups

The purpose is to communicate, debate or try to convince parliamentarians or government executives to make a particular decision to address particular or general interests.

Explanation:

Interest groups is the name given to the activity of influence of an organized group with the objective of directly interfering in the decisions of the public power, especially of the legislative power, in favor of causes or objectives defended by the group through an intermediary

first paragraph (and busy all the night ,with a silence deep and white )

it would have to be gasioline