Which of These Was not a Reason for the Onset

Which of these was not a reason for the onset of the Spanish-American War?

A) The explosion of the Maine
B) Spain's supposed harsh treatment of the Cubans
C) An intercepted letter in which the Mexican ambassador described President McKinley in a very unflattering way
D) The Rough Riders wanted to make a name for themselves
E) Newspapers published graphic details of Spanish atrocities