Which words give the clue that this is a cause and effect passage?

In August of 1964, North Vietnamese torpedo boats fired on American destroyers in the Gulf of Tonkin. The North Vietnamese said the ships were inside North Vietnamese waters. The United States claimed the attack was illegal.

In response, Congress, at the urging of President Johnson, passed the Gulf of Tonkin Resolution. It gave the president the power to take necessary actions to prevent further acts of aggression.

Question 8 options:

necessary action

The attack was illegal.

in response

in August of 1964

- in response