Final answer:
MoveOn.org is not an example of a single-issue group because it focuses on a wide range of political issues, unlike the other listed organizations that each focus on a specific issue.
Step-by-step explanation:
The student asked which of the listed organizations is NOT an example of a single-issue group. While the Sierra Club, National Rifle Association (NRA), Izaak Walton League, and right-to-life groups are all examples of organizations that fall into this category due to their focus on specific issues such as the environment, gun rights, outdoor conservation, and anti-abortion respectively, MoveOn.org does not fit within this definition. MoveOn.org is a broader-based political advocacy group that focuses on a wide range of issues, which disqualifies it as a single-issue group.