Step 1: Understanding the Concept:
The question asks for the date marking the end of the Cold War, a period of geopolitical tension between the United States and the Soviet Union and their respective allies.
Step 2: Detailed Explanation:
While the end of the Cold War can be seen as a process, the most definitive event that marks its conclusion is the dissolution of the Soviet Union (USSR). The USSR was officially dissolved on December 26, 1991. This event formally ended the bipolar world order that had characterized the Cold War era. Other events like the fall of the Berlin Wall in 1989 are symbolic milestones, but the official end is tied to the collapse of the Soviet Union.
Step 3: Final Answer:
The Cold War is considered to have ended with the dissolution of the Soviet Union in December 1991. Therefore, option (A) is the most accurate answer.