India was partitioned in 1947 as a consequence of the constitutional formula contained in which of the following official plans or declarations?

Introduction / Context:
This question focuses on the constitutional and political steps that directly led to the partition of India in 1947. Several important plans and announcements were made by the British government in the mid 1940s, including the Cabinet Mission Plan, Attlee's declaration and finally the June 3 Plan, also called the Mountbatten Plan. Knowing which of these actually contained the operative formula for partition is crucial for a clear understanding of the decolonisation process.

Given Data / Assumptions:

• The year of partition is 1947.
• Multiple British plans and declarations are listed as options.
• Only one of these contained the detailed formula that directly led to the partition.
• The question asks which specific plan or declaration contained that operative formula.

Concept / Approach:
The approach is to recall the role of each measure. The Cabinet Mission Plan tried to keep India united within a loose federal framework and did not itself implement partition. The Attlee Declaration announced the intent to transfer power but did not spell out the final territorial scheme. The Indian Independence Act 1947 legally enacted the partition already decided. The June 3 Plan, announced by Lord Mountbatten, outlined the concrete constitutional scheme under which India would be partitioned into two dominions, India and Pakistan. Therefore we identify which option corresponds to that June 3 Plan.

Step-by-Step Solution:
Step 1: Recall that the Cabinet Mission Plan (1946) proposed a united India with groupings of provinces and aimed to avoid partition. Step 2: Attlee's declaration in February 1947 stated that the British would leave India by a fixed deadline but did not contain the final partition formula. Step 3: The June 3 Plan, also called the Mountbatten Plan, specifically laid down that provinces could decide whether to join India or Pakistan and described the method of partition. Step 4: The Indian Independence Act 1947 implemented the decisions of the June 3 Plan in legal form. Step 5: Therefore, the plan which actually contained the constitutional formula of partition was the June 3 or Mountbatten Plan.

Verification / Alternative check:
Any standard text on modern Indian history mentions that the June 3 Plan provided the framework for the partition of British India into India and Pakistan. The Indian Independence Act followed that framework. The Cabinet Mission Plan is always described as an attempt to preserve unity, and Attlee's declaration is treated as a political commitment to transfer power rather than as a detailed partition formula. This confirms that option "June 3 Plan or Mountbatten Plan" is correct.

Why Other Options Are Wrong:
Cabinet Mission Plan: This plan aimed to keep India united through a complex federal structure and did not prescribe partition as the operative solution.
Attlee Declaration of 20 February 1947: It announced the decision to leave India but did not itself lay down the final partition scheme.
Indian Independence Act 1947: It translated the already agreed partition plan into law but did not originate the constitutional formula; that came from the June 3 Plan.

Common Pitfalls:
Students often confuse the chronological sequence of these measures and think that whichever act or declaration is closest to 1947 must be the source of the partition formula. Another error is to assume that the Indian Independence Act was itself the "plan", when in fact it was the legal implementation of the Mountbatten Plan. It is important to separate announcing the intention to leave, proposing a united framework, and finally laying down the specific conditions of partition.

Final Answer:
India was partitioned as a consequence of the formula contained in the June 3 Plan or Mountbatten Plan.