Question

why did the zimmerman telegram upset the united states? check all of the reasons that apply. it included comments about the cowardice of the united states it threatened that germany would invade mexico it declared the renewal of unlimited submarine warfare it proposed an alliance between germany and mexico against the united states.

Explanation:

The Zimmerman Telegram proposed a German - Mexican alliance against the US and declared renewal of unrestricted submarine warfare. These were major threats to US interests. There were no comments about US cowardice in the telegram, and the threat was for Mexico to join Germany in war in return for getting back territory from the US, not Germany invading Mexico directly.

Answer:

It declared the renewal of unlimited submarine warfare
It proposed an alliance between Germany and Mexico against the United States.