Final answer:
The correct answer is a. The USS Maine's destruction led to the start of the Spanish-American War, marking the United States' transition into an imperial power and a significant geopolitical shift.
Step-by-step explanation:
The destruction of the USS Maine led to the start of the Spanish-American War. This tragic event became a catalyst for the United States' entry into a conflict predominantly about Cuban independence from Spain.
On February 15, 1898, the explosion of the USS Maine in Havana harbor killed over 250 American sailors. The immediate cause was blamed on a Spanish mine by the sensationalist yellow press, fueling the public demand for war against Spain. Although later investigations suggested the explosion might have been an internal accident, the outcry led President McKinley to call for war, which Congress declared on April 25, 1898.
The Spanish-American War marked a significant turning point as it marked the emergence of the United States as an imperial power and altered the global balance of power as the twentieth century began.