Concept:Some cities are planned and built deliberately to serve as national capitals, rather than growing naturally as commercial or industrial centres.
Explanation:Canberra is a purpose-built capital of Australia.
Abuja was planned as the federal capital of Nigeria.
Brasilia was specially constructed as the capital of Brazil.
Chicago is a major city in the USA, not a seat of power.
Ruhr is an industrial district in Germany, not a capital.
New Delhi is a capital, but Kolkata and the Ruhr are not purpose-built seats of power.
Only the set containing Canberra, Abuja and Brasilia lists cities developed specifically as seats of government.
Answer:C. Canberra, Abuja and Brasilia