What is considered the most essential feature of the parliamentary form of government as adopted in India under its Constitution?

Introduction / Context:
India follows a parliamentary form of government at the Union and state levels, inspired largely by the British model. Many features characterise this system, such as a nominal head of state, a real head of government drawn from the legislature and collective responsibility. This question asks you to identify the core or most essential feature that distinguishes the parliamentary system from other forms like the presidential system.

Given Data / Assumptions:

The question is about the essential feature of the parliamentary form of government.

Options mention sovereignty of Parliament, written constitution, accountability of the executive and independent judiciary.

We assume awareness that some of these features also exist in other systems, so we must select the one that best defines the parliamentary system.

Concept / Approach:
The defining characteristic of a parliamentary system is that the executive (Council of Ministers headed by the Prime Minister) is collectively responsible to the legislature, usually the lower house. If it loses the confidence of the majority, it must resign. This feature of political and legal accountability sets the parliamentary system apart from a presidential system, where the executive does not depend on the confidence of the legislature for its survival. While a written constitution and independent judiciary are important, they are not unique to the parliamentary system.

Step-by-Step Solution:
Step 1: Recall that in India the Council of Ministers is collectively responsible to the Lok Sabha. Step 2: If the Lok Sabha passes a no confidence motion, the Council of Ministers must resign, showing direct accountability. Step 3: Understand that this relationship between executive and legislature is central to the idea of cabinet government. Step 4: Note that other options like written constitution and independent judiciary describe broader constitutional features that may exist in both parliamentary and presidential systems. Step 5: Therefore, the most essential feature in a parliamentary system is accountability of the executive to the legislature.

Verification / Alternative check:
You can verify this by comparing India with a classic presidential system such as that of the United States. In the United States, the President has a fixed term and does not lose office simply because Congress passes a vote of no confidence. This difference in how the executive is tied to the legislature is the key distinction. Since the Indian system requires the ministry to enjoy the confidence of the Lok Sabha at all times, accountability of the executive to the legislature emerges as the central feature.

Why Other Options Are Wrong:
Sovereignty of the Parliament: In India, Parliament is powerful but not fully sovereign in the British sense because the Constitution is supreme and judicial review exists.
Written constitution: A written constitution can be found in both parliamentary and presidential systems. It is important but not unique to the parliamentary form.
Independent judiciary: An independent judiciary is a feature of many democratic systems regardless of whether they follow a parliamentary or presidential model.

Common Pitfalls:
Students sometimes pick sovereignty of Parliament because they associate the parliamentary model with the British system where Parliament is supreme. However, in India the Constitution is supreme, and the courts can strike down laws. Another confusion arises when candidates treat general democratic institutions like an independent judiciary as defining features of a specific system. To avoid this, always remember that what truly distinguishes the parliamentary form is the political responsibility of the executive to the legislature through mechanisms like confidence and no confidence motions.

Final Answer:
The most essential feature of the parliamentary form of government is the accountability of the executive to the legislature.