In the history of India's population growth, which decade is commonly referred to as the period of a \"great leap forward\"?

Introduction / Context:
This question belongs to Indian demographic history. Different periods in the growth of India's population have been given descriptive names such as the stationary phase, the period of steady growth, and the period of a great leap forward. Understanding which decade corresponds to which phase is important in economic geography and population studies.

Given Data / Assumptions:

• The question uses the phrase \"great leap forward\" for Indian population growth.
• We need to identify the correct decade from the options given.
• The answer is based on census wise analysis of population growth rates.

Concept / Approach:
Indian demographic history is often divided using census data. Up to 1921, population growth was slow and unstable, called a period of stationary or fluctuating growth. From 1921 to 1951, growth became more regular but still moderate. The decade 1951 to 1961 is termed the period of a great leap forward, when population growth accelerated sharply due to a fall in death rates, improvement in health facilities, and continued high birth rates. Later decades are associated with the population explosion and then a gradual decline in growth rates.

Step-by-Step Solution:
Step 1: Remember that 1921 is known as the demographic divide, marking a shift from fluctuating to more consistent growth.Step 2: The period 1921 to 1951 shows steady growth but not the sharpest increase.Step 3: The decade 1951 to 1961 is characterised by significant improvement in medical care and control of epidemics, reducing mortality.Step 4: Birth rates remained high in this decade, so natural increase accelerated strongly.Step 5: For this reason, 1951 to 1961 is described as the period of a great leap forward in population growth.

Verification / Alternative Check:
You can verify by recalling labels used in standard geography textbooks. 1901 to 1921 is the period of stagnant growth. 1921 to 1951 is the period of steady growth. 1951 to 1981 is generally considered the population explosion phase, within which 1951 to 1961 stands out as a leap forward. Therefore, among the options given, 1951 to 1961 fits the description most closely.

Why Other Options Are Wrong:
The decade 1921 to 1931 still falls early in the steady growth phase and is not identified as the great leap forward. The decade 1941 to 1951 includes the Second World War period and partition related disturbances and is not labelled this way. The decades 1961 to 1971 and 1971 to 1981 had high growth but are more often associated with the broader population explosion term rather than the specific phrase used in the question.

Common Pitfalls:
A frequent mistake is to confuse the population explosion overall with the specific decade called a great leap forward. Students also sometimes mix up the labels of demographic phases, especially when they do not revise the census wise classification just before the exam. Making a small timeline of key census years and associated names is a simple but powerful revision tool.

Final Answer:
The decade commonly described as a period of a great leap forward in India's population growth is 1951 - 1961.