What Incident Was Responsible for the United States Going to War

What incident was responsible for the United States going to war with Spain?

A) a private letter of President McKinley's that was published in the New York Journal that insulted the Spanish leadership
B) a surprise attack by the Spanish on the United States' base at Guantanamo Bay
C) the explosion and deaths onboard the USS Maine,a battle cruiser sent to Havana to prevent attacks on American interests in Cuba
D) an assassination attempt on President McKinley that was blamed on Spanish agents