ONDC, an initiative of the Department for Promotion of Industry and Internal Trade, stands for:

The correct answer is D, both A and C. In an auction the price is not fixed by the seller but is discovered from what buyers are willing to bid, and this way of trading appears at two levels. Between businesses, industrial exchanges and procurement portals run reverse auctions and dynamic pricing for bulk material, which is B2B commerce, so option A is part of the answer. Between individuals, classified and auction platforms let one consumer bid for goods another consumer is selling, which is C2C commerce, so option C is also part of the answer. Option B, C2B commerce, is where an individual supplies a service or content to a firm, as a freelancer or a stock photographer does, and the price there is normally negotiated rather than auctioned. Because both the business-to-business and the consumer-to-consumer levels fit, the combined option D is right.

The correct answer is C, C2C, which stands for consumer to consumer. Here both sides of the deal are individuals and the website only provides the listing, the search and sometimes the payment and dispute machinery, earning a fee or advertising revenue rather than a trading margin. Classified and auction platforms such as OLX, Quikr and eBay's classifieds are the standard examples. Option A, B2B or business to business, covers trade between firms, as on IndiaMART or Alibaba, where a manufacturer buys raw material or components. Option B, B2C or business to consumer, is the familiar retail model in which a company sells directly to the shopper, as Amazon and Flipkart do. Option D, G2C or government to citizen, covers public services delivered online, such as railway ticketing through IRCTC or an online passport application. Identify the model by naming the two parties first, then matching the letters.

The correct answer is B, the National Payments Corporation of India. NPCI, set up in 2008 as the umbrella organisation for retail payments in the country, built and runs UPI, which lets a user link several bank accounts to one mobile application and transfer money instantly using a virtual payment address, without sharing account numbers. NPCI also operates RuPay, IMPS, AEPS, the *99# USSD service and the BHIM application released in 2016. Option A, the Reserve Bank of India, is the regulator that authorised and oversees NPCI and the payment systems, but it does not operate UPI itself; the distinction between regulating and operating is the trap in this question. Option C, the State Bank of India, is only one of the member banks on the network. Option D, SEBI, regulates the securities market and has no role in retail payments. Remember the pairing: RBI regulates, NPCI operates.

The correct answer is A, commercial transactions carried out through wireless handheld devices. M-commerce, or mobile commerce, is the part of electronic commerce conducted on smartphones, tablets and even feature phones over a wireless network, and the term is credited to Kevin Duffey in 1997. Because the device is personal, portable and location-aware, m-commerce supports mobile banking, mobile ticketing with a QR code, scan-and-pay at a counter, contactless NFC payment, hyperlocal delivery and in-app purchase. Option B describes Electronic Data Interchange, or EDI, the older standard by which firms exchange purchase orders and invoices between their computer systems. Option C is government to government dealing, usually written G2G, which is part of e-governance rather than of mobile commerce. Option D is simply advertising through a mass medium, with no electronic transaction at all, and advertising is only one activity that may support commerce.

The correct answer is A, SSL or TLS encryption. HTTPS is HTTP carried inside a protected channel: the browser and the server first exchange a digital certificate and agree on keys, after which card numbers, passwords and addresses travel as cipher text that an eavesdropper on the network cannot read. The older protocol was Secure Sockets Layer (SSL) and the current one is Transport Layer Security (TLS), which is why both names appear in textbooks and why the padlock icon is shown in the address bar. Option B, SMTP, is the protocol that carries outgoing e-mail and has nothing to do with web security. Option C, static IP addressing, merely means a device keeps a fixed network address; it does not encrypt anything. Option D, SQL, is the language used to query databases, and a careless implementation of it is itself a security weakness known as SQL injection. For an online payment, HTTPS plus a one-time password is the minimum a shopper should expect.