Question

How did the Americans contribute to the Allied victory in World War I?

The Americans strengthened the Allied counterattacks.
The Americans had superior weapons and technology.
The Americans had more experience in trench warfare.

Answer 1

I think you are asking for only one, so it would be the first one. When the Americans joined the war, they helped out Britain and France so much and this eventually lead to the massive counter attack on d-day.

Answer 2

I would say the answer is the first one