India's population reached the landmark figure of 100 crore (one billion) in which month and year?

Introduction / Context:
Crossing the population mark of 100 crore or one billion was a significant demographic milestone for India. It highlighted the scale of challenges and opportunities in planning for health, education, employment, and infrastructure. This question focuses on the specific month and year when India is estimated to have reached this landmark population figure, an important factual detail in the population geography of India.

Given Data / Assumptions:

• The question asks when India reached a population of 100 crore.
• The options list different months and years around 2000 and 2001.
• We assume the commonly accepted official estimate used in demographic studies.
• The emphasis is on the landmark date, not on the exact day within the month.

Concept / Approach:
Census data and population projections are used to estimate when major thresholds are crossed. According to widely used demographic estimates, India reached the population of one billion around May 2000. The 2001 Census later confirmed that the population had already crossed this mark by the census date. Therefore, among the given options, May 2000 is the correct month and year associated with the 100 crore milestone.

Step-by-Step Solution:
Step 1: Recall that India conducted a census in 2001, which recorded a population above one billion. Step 2: Understand that demographic projections back calculate when the one billion threshold was likely crossed. Step 3: Standard references and exam guides often state that India crossed the 100 crore mark in May 2000. Step 4: Compare this with the options, which include May 2000 and other nearby dates such as May 2001 and May 2002. Step 5: Match the known milestone date with May 2000 as the correct answer.

Verification / Alternative check:
To verify, students can look up population history summaries, which typically mention that India became the second country after China to cross the one billion population mark around May 2000. The 2001 Census figures provide a firm total, and demographic models indicate that the one billion line had been passed roughly a year earlier. Since exam questions rely on this widely reported date, May 2000 is the answer expected.

Why Other Options Are Wrong:
May 2001 is too late, because by that time the population had already exceeded one billion according to census data.
May 2002 and May 2003 are even further from the commonly cited estimate and do not match demographic studies of the period.
April 2000 is close in time but does not correspond to the specific month widely used in official and educational references, which is May 2000.

Common Pitfalls:
Learners may confuse the year of the census that confirmed the one billion figure with the estimated year when the threshold was crossed. Since the census took place in 2001, some students wrongly select May 2001 instead of May 2000. Another mistake is to focus only on the year and ignore the month, even though exams often test both pieces of information. Remembering the single phrase India crossed one billion population in May 2000 helps avoid such confusion.

Final Answer:
India's population reached the 100 crore (one billion) mark in May 2000.