Question

What is the main idea of this passage from the 9/11 Commission Report?

The United States had no chance at stopping the attacks and should not have tried to do so.

The United States might not have been able to stop the attacks, but it could have made a better effort to do so.

The United States tried its best to stop the attacks, but terrorist groups were too resourceful to be stopped.
Since the plotters were flexible and resourceful, we cannot know whether any single step or series of steps would have defeated them. What we can say with confidence is that none of the measures adopted by the U.S. government from 1998 to 2001 disturbed or even delayed the progress of the al–Qaeda plot. Across the government, there were failures of imagination, policy, capabilities, and management.

–The 9/11 Commission Report
2004

Answer 1

Answer: 2.

Why: The passage says we can't know if any single action would have stopped the plot but states that "none of the measures adopted... disturbed or even delayed the progress" and cites "failures of imagination, policy, capabilities, and management," implying the U.S. could have made a better effort.