Answer: d. a letter from the Spanish ambassador
Explanation: On February 9th 1898, The Spanish ambassador Enrique Dupuy de Lôme wrote a letter to the Foreign Minister of Spain, Don José Canalejas in the letter, de Lôme’s opinion about the Spanish involvement in Cuba and the diplomacy of US President McKinley’s was revealed.
In the letter, the Spanish ambassador Enrique Dupuy de Lôme criticized American President William McKinley by calling him weak and concerned only with gaining the favor of the crowd.
The words contained in the publicized seized Spanish letter caused an international uproar which contributed in the anti-Spanish and pro-war feelings in the United States.
The publication of the letter generated a lot of public support for a war against Spain concerning independence for the Spanish colony of Cuba.