Step 1: Understanding the Concept:
This question deals with the birth of Bangladesh and the regional dynamics of 1971.
Step 2: Detailed Explanation:
Statement I: Following the 1971 Indo-Pak war, the eastern wing of Pakistan broke away to form the sovereign state of Bangladesh. This is correct.
Statement II: India supported the Mukti Bahini (liberation force) and intervened militarily against the Pakistani army, which directly led to the independence of the new nation. Therefore, Statement II is not only true but is also the direct cause/reason for the event described in Statement I.
Step 3: Final Answer:
Both are correct, and Statement II explains Statement I.