Final answer:
Interest groups use litigation as a strategy of influence by filing amicus curiae briefs, financing lawsuits, and bringing suit directly on behalf of the group. Option a. is correct.
Step-by-step explanation:
Interest groups use litigation as a strategy of influence by filing amicus curiae briefs, financing lawsuits, and bringing suit directly on behalf of the group. Amicus curiae briefs allow interest groups to present their official positions on cases being heard before a court. Interest groups can also use their resources to file cases in lower courts or have appeals heard in higher courts.
For example, the Sierra Club and Southern Border Communities Coalition filed suit against President Trump for his use of executive power to fund and build a wall on the southern border of the United States.