The 2021 Census of India faced challenges due to:

The correct answer is: a) COVID-19 pandemic.

The 2021 Census of India was the 20th national census conducted in India. It was conducted from 1st April to 30th September 2021. The census was originally scheduled to be conducted in 2020, but it was postponed due to the COVID-19 pandemic.

The COVID-19 pandemic had a significant impact on the 2021 Census of India. The pandemic caused a number of challenges, including:

• The closure of many offices and businesses, which made it difficult to collect data.
• The movement restrictions imposed by the government, which made it difficult to reach remote areas.
• The fear of contracting the virus, which made many people reluctant to participate in the census.

Despite these challenges, the 2021 Census of India was successfully completed. The census provides a valuable snapshot of the population of India and will be used to plan for future development.

The other options are incorrect because:

• Natural disasters did not have a significant impact on the 2021 Census of India.
• Political unrest did not have a significant impact on the 2021 Census of India.
• Technical issues did not have a significant impact on the 2021 Census of India.