The correct answer is C) victory over Spain in the Spanish-American War.
The event that contributed most to the United States being recognized as an international power was the victory over Spain in the Spanish-American War.
The Spanish-American War started in 1898 that originated with the demand for Cuba to gain independence from Spain. The UnitedStates supported Cuba and sent a ship -the USS Maine. to protect its citizens and property of the Island. The Spanish sank the ship and declared war on the US on April 24, 1898.
The United States won the war and signed the Treaty of Paris on December 10, 1898. Spain ceded Puerto Rico and Guam to the US, gave independence to Cuba and left the Philippines.