Consider the following airports : 1. Donyi Polo Airport 2. Kushinagar International Airport 3. Vijayawada International Airport In the recent past, which of the above have been constructed as Greenfield projects?

Option (a) is correct because Donyi Polo Airport (Arunachal Pradesh) and Kushinagar International Airport (Uttar Pradesh) were both developed as entirely new facilities on undeveloped land under the government's Greenfield Airports Policy. Option (d) is the most tempting wrong choice, but it is incorrect because Vijayawada International Airport is a Brownfield project involving the expansion and modernization of an existing facility rather than a new construction from scratch. The core concept being tested is the distinction between Greenfield (new site) and Brownfield (upgraded site) infrastructure development within India's civil aviation sector.