The correct answer is B.
The USS Maine battle ship was quietly riding anchor in Havana harbor, Cuba. At 9.40 pm on the night of February 15th, 1898, the ship was blown up apparently by a mine, in an explosion which tore out its bottom and sank, killing 260 officers and men on board.
No one ever established exactly what caused the explosion but it nevertheless resulted in the brief American - Spanish war because America strongly suspected the Spanish were the culprits.