Under Section 12(2) of the Airports Authority of India Act, 1994, which of the following is described as a duty (as distinguished from a discretionary function) of the Authority?

Section 12(2) imposes a duty - rather than a mere discretionary power - on the Authority to provide air traffic service and air transport service at any airport and civil enclave. This is distinguished from Section 12(1), which makes it a function (subject to Central Government rules) to manage airports, civil enclaves, and aeronautical communication stations efficiently, and from Section 12(3), which lists an extensive, non-exhaustive range of activities the Authority "may" undertake, such as constructing runways and terminals, establishing hotels and restaurants, and providing consultancy services. The mandatory phrasing of sub-section (2) reflects the core, non-negotiable public-service character of air traffic and transport service provision, as opposed to the Authority's broader commercial and developmental activities.