B. They promote policies that support their beliefs.
Special interest groups in politics are also known as "advocacy groups" or "lobbying groups." They have a particular area of interest or policies that they'd like to see in place in the government. So they will spend a lot of money and effort seeking to convince those in government to adopt policies that are aligned with the interests or priorities of the interest group. The National Rifle Association (NRA) would be an example of a powerful lobbying group of this sort. So also would be Greenpeace, which is an environmental interest group. There are many interest groups supporting many different causes or concerns.
