In the history of India Five Year Plans, the Mahalanobis model of growth is mainly associated with which particular plan period?

Introduction / Context:
This question relates to the planning history of India and the use of specific growth models in different Five Year Plans. The Mahalanobis model, named after statistician P. C. Mahalanobis, played an important role in shaping India industrial strategy. Understanding which plan adopted this model helps candidates connect theory with actual policy implementation.

Given Data / Assumptions:

• The question asks about the association of the Mahalanobis model with a particular Five Year Plan.
• Options list the first four Five Year Plans and one additional later plan.
• The Mahalanobis model is a specific type of growth model focusing on heavy industry.
• We assume the context is official Indian planning rather than academic proposals only.

Concept / Approach:
The Mahalanobis model emphasised rapid industrialisation through heavy industries and capital goods. It argued that allocating a higher share of investment to these sectors would raise long term growth by expanding productive capacity. In India, this approach strongly influenced the Second Five Year Plan, which shifted focus from agriculture centric development in the First Plan towards industrial expansion. Therefore, identifying the plan that stressed heavy industry and capital goods investment is the key to solving the question.

Step-by-Step Solution:
Step 1: Recall the broad focus of each early Five Year Plan.Step 2: The First Five Year Plan mainly concentrated on agriculture, irrigation and rehabilitation after independence.Step 3: The Second Five Year Plan emphasised industrialisation, particularly heavy and basic industries, guided by the Mahalanobis model.Step 4: The Third and Fourth Plans had more diversified objectives including agriculture, industry and self reliance, but the core Mahalanobis framework was already established earlier.Step 5: Conclude that the Mahalanobis model is primarily associated with the Second Five Year Plan.

Verification / Alternative check:
Standard references on Indian economic planning describe the Second Five Year Plan as being based on the Mahalanobis model. The plan emphasised rapid industrial growth and a high share of investment in capital goods industries, which matches the theoretical structure of the model. No other plan is described in textbooks as being formally based on this specific framework, which confirms the answer.

Why Other Options Are Wrong:
The First Five Year Plan followed a different model with focus on agriculture and the Harrod Domar type approach, not the Mahalanobis heavy industry model.
The Third Five Year Plan aimed at balanced growth in agriculture and industry but did not introduce the Mahalanobis model for the first time.
The Fourth and Fifth Plans dealt with issues like stability, poverty removal and self reliance rather than introducing a new basic growth model.
The Fifth Plan option is included as a distractor since it is often mentioned for targets like poverty alleviation, not for the Mahalanobis framework.

Common Pitfalls:
The main confusion arises between the First and Second Plans. Some candidates incorrectly assume that the industrial push began from the very first plan or confuse the Harrod Domar model with the Mahalanobis model. Others may misremember later plans as being associated with heavy industry emphasis because they feature public sector enterprises, but the original theoretical link belongs to the Second Plan.

Final Answer:
The Mahalanobis model is mainly associated with the Second Five Year Plan of India.