The correct answer is option 'C', the Third Five Year Plan. Let's understand why this plan focused on stabilizing population growth as the central feature of planning.

I. Introduction to the Third Five Year Plan:
The Third Five Year Plan in India was formulated for the period of 1961-1966. It aimed to continue the development initiatives started in the previous plans and address various socio-economic challenges faced by the country.

II. Objective of the Third Five Year Plan:
The main objective of the Third Five Year Plan was to achieve a higher rate of economic growth while also ensuring social justice and equity. One of the key aspects of this plan was to stabilize the population growth in India.

III. Population Growth as the Central Feature:
The Third Five Year Plan recognized that the rapidly growing population in India was putting immense pressure on the country's resources and infrastructure. To address this issue, the plan emphasized the need to control population growth through various measures.

IV. Policies and Measures:
1. Family Planning: The plan emphasized the promotion of family planning methods to control population growth. It aimed to encourage smaller family sizes through the use of contraceptives, education, and awareness campaigns.

2. Health and Maternal Care: The plan focused on improving healthcare facilities, particularly in rural areas, to ensure better maternal and child health. This was seen as a means to reduce infant mortality rates and encourage smaller family sizes.

3. Education and Awareness: The Third Five Year Plan recognized the importance of education and awareness in creating a population that understands the benefits of family planning. It aimed to spread knowledge about contraception and reproductive health through various educational programs.

4. Incentives and Rewards: The plan proposed providing incentives and rewards to individuals and families who adopted family planning measures. This included financial incentives, access to healthcare facilities, and other benefits to encourage the adoption of family planning methods.

V. Impact and Evaluation:
The Third Five Year Plan's focus on population stabilization had a significant impact on the population growth rate in India. It led to increased awareness, higher contraceptive use, and a decline in population growth rates over time.

In conclusion, the Third Five Year Plan in India, which spanned from 1961 to 1966, made stabilizing population growth the central feature of planning. It recognized the need to control population growth to ensure sustainable development and implemented various policies and measures to achieve this objective.