Final answer:
A single-issue interest group focuses on advocating for a specific policy or cause. One example of a single-issue interest group is the National Rifle Association (NRA).
Step-by-step explanation:
A single-issue interest group focuses on advocating for a specific policy or cause. It is a type of interest group that solely concentrates on one narrow issue. One example of a single-issue interest group is the National Rifle Association (NRA), which advocates for gun rights in the United States.