Step 1: Understanding the Concept:
This question deals with the integration of princely states into the Dominion of India after independence in 1947.
Step 2: Detailed Explanation:
At the time of Indian independence in 1947, the princely state of Hyderabad, ruled by the Nizam, initially chose to remain independent. After negotiations failed, the Indian government launched a military operation named Operation Polo. The operation took place in September 1948, leading to the surrender of the Nizam's army and the annexation of Hyderabad into the Indian Union. The process was completed on September 18, 1948.
Step 3: Final Answer:
Hyderabad merged with India in 1948. Therefore, option (A) is the correct answer.