What possible disadvantage of interest groups does this scenario illustrate: An interest group representing auto manufactuers runs ads opposing a high speed train project, even though the the train would reduce commute times for many citizens

They focus primarily on the interests of their members, not on the public good.

Explanation:

Given that the high-speed train project would reduce commute times for many citizens thereby benefiting the public generally.

An interest group representing auto manufacturers running advertisements opposing such a project shows that the disadvantage of the interest groups is that "They focus primarily on the interests of their members, not on the public good."

i really dont know the answer

he believed that congress would be better not dealing with "lobbyists", or people who seek to influence (a politician or public official) on an issue, since historically, they had problems with these kinds of people. he thought lobbying produces benefits, but should be carefully monitored.