Which would be considered a single - issue interest group

Some interest groups who sometimes advocates or against for single issue is considered as single-issue interest group.  

Explanation:

There are three types of interest group. Single interest group is one of them. The main role of single interest group is work on small issues like gas tax, abortion, minimum wages, healthcare and union. Because of single issue they never come in existence and form a party. They have very fixed goal.  NRA is most effective single interest group.  

i am pretty sure it is d.

a factory opens that mass-produces light bulbs.

explanation:

not sure if that's an answer to your questions but this is an example! : )