Kanpur and Lucknow cities of U.P. became million cities as per the census of India in the year

The correct answer is C. Kanpur crossed the million mark in the 1971 census, and Lucknow followed in the 1981 census. A city is called a million city when its population reaches 10 lakh or more, and the census is the only official source for this.

• A: Kanpur and Lucknow were both well under 10 lakh in 1951 and 1961. Kanpur was still below the mark in 1961, so the 1961 date for Kanpur is wrong.
• B: Kanpur was just under 10 lakh in 1961, so it did not qualify then. Lucknow was still under 10 lakh in 1971, so 1971 is wrong for Lucknow.
• D: Kanpur had already crossed 10 lakh by 1971, so it could not become a million city in 1981. Lucknow's entry in 1981 is right, but the pairing fails on Kanpur.

The concept is simple: a decadal census tracks urban growth, and the million-city tag is a shorthand for big-city pressure on water, housing, transport and civic governance. For Mains, this links to urbanisation, the 74th Constitutional Amendment and Smart Cities planning. The count has grown since then; Census 2011 listed 53 million-plus cities in India.

Trap: Aspirants often guess the later decade for both cities, assuming they grew steadily in the same period. Check each city's census separately.