The correct answer is "Congress was able to override a presidential veto of the act."
The War Powers Act was a federal law that limits the ability of the president to commit the US military. Thanks to this law, the US president cannot commit the US to an armed conflict unless he/she has Congressional approval. Even though President Richard Nixon tried to stop this law from happening by vetoing it, Congress overrode this veto with a 2/3rds vote in each part of Congress to ensure that it became a law.
