At what rate did the trial generate secure keys, and what error rate did the link hold?

The correct answer is 5.56 km. That is the span over which the country's first free-space Quantum Key Distribution link was established, between the BISAG-N campus and IIT Gandhinagar, in a field trial run on the night of 27 and 28 September. Options A, C and D are wrong because each names a distance other than the one achieved, and in a question of this type the figure itself is the whole answer. The distance matters for a reason worth understanding rather than merely memorising: sending single photons through open air means fighting turbulence, scattering and the problem of keeping a narrow beam locked on a receiver kilometres away, which is why a Pointing, Acquisition and Tracking system was needed. The team described the result as a step towards longer-distance quantum-secure networks and towards quantum communication by satellite, so later figures may well be larger.

The correct answer is QNu Labs, BISAG-N and IIT Gandhinagar. QNu Labs supplied the hardware QKD device Armos, BISAG-N contributed the post-quantum cryptography platform Vedic Kavach along with one end of the link, and IIT Gandhinagar hosted the other end and provided the field setting. Option A is wrong because neither the space agency nor the defence research organisation is named in this demonstration, although both work on allied technologies. Option C is wrong because the telecom research centre, the public sector electronics firm and the Bengaluru institute named there had no part in this particular trial. Option D is wrong on the same ground. The partnership is worth remembering as a shape as much as a list: a private quantum technology firm, an autonomous scientific society under the Ministry of Electronics and Information Technology, and an IIT supplying the academic and field component.

The correct answer is Vedic Kavach, the post-quantum cryptography platform built by BISAG-N. The keys produced by the quantum link were integrated with it, and test messages were then encrypted and decrypted from end to end. Option A is a trap worth noticing: Armos is also part of this story, but it is QNu Labs' hardware QKD device that generates the keys over the free-space optical channel, not the software platform that consumes them. Keeping the two names apart is the main thing this question tests. Option C is wrong because no platform of that name features in the demonstration. Option D is wrong as well and is simply a plausible sounding invention. Remember the division of labour: Armos is hardware and makes the keys, Vedic Kavach is software, adds post-quantum cryptography and quantum random number generation, and uses them.

The correct answer is the Universal Service Obligation Fund. The fund was created under the Indian Telegraph (Amendment) Act, 2003, and the Telecommunications Act, 2023 renamed it Digital Bharat Nidhi. It is an attached office of the Department of Telecommunications and its mandate is to support telecom access in underserved rural, remote and urban areas. Options A, C and D are plausible sounding names but none of them is the earlier name of this fund. Remember what the fund pays for besides BharatNet: the 4G Saturation Project and mobile services in uncovered parts of aspirational districts, Left Wing Extremism affected areas, Himalayan and border areas, islands and the North Eastern states. The Maharashtra agreement for the Amended BharatNet Programme was signed by this very fund, so B is the answer.

The correct answer is MahaNet Digital Infrastructure Limited, usually written as MDIL. The project in Maharashtra will be implemented through MDIL, which is why it is one of the five parties to the agreement. Option B is wrong: Bharat Sanchar Nigam Limited signed the agreement and its Director for Enterprise Business attended, but the execution rests with MDIL. Option C is wrong for the same reason, as MahaIT is a signatory whose Managing Director was present, not the implementing agency. Option D is wrong because that company is not among the five signatories at all; the others are Digital Bharat Nidhi of the Department of Telecommunications and the Government of Maharashtra. Reading the list of signatories and the line naming the implementing agency separately is how you avoid the trap, so A is right.