<em>False.</em>
Explanation:
Although the sinking of the Lusitania was fuel for the United States to enter World War I, it was not the direct cause of it. The United States actually entered the war a few years later, but people still remembered the Lusitania.
Although there were numerous occurrences that happened that finally made the United States declare war on Germany, the sinking of the Lusitania included, the biggest reason for them joining the war was because of the Zimmerman Telegram.
In 1917, the British decoded a secret message that was for Mexico, from Germany. This telegram is known as the Zimmerman Telegram, and in it stated that if Mexico joined forces with Germany, against the United States, they would get numerous territories in America when Germany won the war.
This was the direct cause of the United States joining World War I. The Zimmerman Telegram finally made President Woodrow Wilson declare war on Germany.
What do you mean by that question
Economic sanctions directly impact the economy of the subjects country. Therefore a trade ban would be an economic sanction. 1 and 4 would be damaging to diplomatic relations but not the economy and 3 is military intervention which is not solely an economic action.
