What event caused the United States to enter World War I?

Sinking of the Lusitania and Zimmerman Telegram

What object did Eris toss among the goddesses to stir dispute? The Cold War primarily involved tensions between the Soviet Union and which country? What is the primary metal extracted from hematite ore? In which country was Lego invented? In Stardew Valley, what company attempts to take over the rural town economy?