At which session of the Indian National Congress did the organisation officially accept the objective of establishing a "socialistic pattern of society" in India?

Introduction / Context:
This question belongs to the area of post independence political history and economic policy. After independence, the Indian National Congress as the ruling party had to articulate a clear long term economic and social vision. The phrase socialistic pattern of society became famous when the Congress officially adopted it as its goal at a particular session. Knowing the name, place and year of that session is a favourite theme in competitive exams.

Given Data / Assumptions:

• We are asked about the specific Congress session where the socialistic pattern of society was accepted as an objective.
• Options include sessions at Bombay 1953, Avadi 1955, Calcutta 1957, Nagpur 1959 and Lahore 1929.
• We assume familiarity with important Congress resolutions and their chronology.

Concept / Approach:
At the Avadi Session of the Indian National Congress in 1955, the Congress officially declared that it stood for a socialistic pattern of society. This meant that planned economic development would aim at reducing inequalities, preventing concentration of wealth and ensuring that the basic needs of the people were met. Later, this idea influenced Five Year Plans and policy measures. Other sessions listed in the options are important for different reasons, such as the Lahore Session of 1929 for the Purna Swaraj resolution, but they are not associated with the adoption of the socialistic pattern.

Step-by-Step Solution:
1. Recall that the term socialistic pattern of society entered official Congress resolutions in the mid 1950s. 2. The Avadi Session held in 1955 is well known for this declaration. 3. Bombay 1953, Calcutta 1957 and Nagpur 1959 were important sessions but did not introduce this exact phrase as the guiding objective. 4. The Lahore Session of 1929 is associated with the demand for complete independence, not with post independence economic policy. 5. Therefore, the correct answer is the Avadi Session of 1955.

Verification / Alternative check:
Standard Indian history and polity texts mention that the Avadi Session of the Congress in 1955 adopted the resolution that the Congress stands for the establishment of a socialistic pattern of society. This fact is repeated in discussions about planning, mixed economy and public sector expansion. None of the other sessions listed in the options are given this specific credit, which confirms that Avadi 1955 is the correct identification.

Why Other Options Are Wrong:

• Bombay Session of 1953: Important for political discussions, but not for formally adopting the socialistic pattern phrase.
• Calcutta Session of 1957: Took place after Avadi and dealt with many issues but did not introduce this objective.
• Nagpur Session of 1959: Associated with other organisational and policy matters, not the first adoption of the socialistic pattern.
• Lahore Session of 1929: Famous for the Purna Swaraj resolution and independence demand, long before independence and planned economic policy debates.

Common Pitfalls:
Candidates sometimes mix up various Congress sessions and their resolutions because there are many important dates to remember. To avoid confusion, link each major phrase with a specific session: Purna Swaraj with Lahore 1929, socialistic pattern of society with Avadi 1955, and so on. Creating a small chart of Congress sessions and key resolutions is a practical revision tool that can reduce such errors in the exam hall.

Final Answer:
The Indian National Congress officially accepted the objective of a socialistic pattern of society at the Avadi Session of 1955.