A Point of Sale (POS) terminal is used primarily to process and complete electronic payments for goods and services. It allows businesses to accept payments from customers using credit or debit cards, mobile wallets, or contactless payments. POS terminals are an essential part of the digital payment ecosystem, providing a secure and efficient way to handle transactions at retail locations, both online and offline.

• The primary purpose of a Point of Sale (POS) terminal in the context of digital payments is to read the information off a customer's credit or debit card securely and accurately. When a customer makes a purchase using a card, the POS terminal plays a crucial role in facilitating the transaction process. Here's how it works:
• Firstly, the customer inserts or swipes their card into the POS terminal, or in more modern setups, they may tap or insert their card if it supports contactless or chip technology. The POS terminal then reads the card's information, including the card number, expiration date, and sometimes additional security information like a CVV code.
• Next, the POS terminal securely transmits this information to the payment processing network, which contacts the card issuer (e.g., the bank that issued the credit or debit card) to verify the transaction details and ensure that the customer has sufficient funds or credit for the purchase.

Upon receiving verification from the card issuer, the POS terminal completes the transaction, and the customer receives a confirmation of the purchase. Additionally, the customer may be prompted to provide a signature or enter a PIN to further authenticate the transaction.

Hence option A is correct.

UPI (Unified Payments Interface) is built over the IMPS infrastructure and allows instant money transfer between any two parties' bank accounts.

Unified Payments Interface (UPI) is a revolutionary payment system developed by the National Payments Corporation of India (NPCI) that operates over the Immediate Payment Service (IMPS) infrastructure. IMPS is an interbank electronic fund transfer service that enables instant and 24x7 transactions.

UPI simplifies the process of transferring funds between bank accounts by providing a single platform that integrates multiple bank accounts, enabling users to make payments and transfer money seamlessly using their smartphones. It allows users to link their bank accounts to a UPI-enabled mobile app and create a Virtual Payment Address (VPA), eliminating the need to share sensitive information like bank account numbers and IFSC codes.

When a user initiates a transaction through UPI, the system securely authenticates the transaction and facilitates the transfer of funds in real-time between the sender and receiver's bank accounts. This instant and convenient method of transferring money has transformed the way people conduct financial transactions in India, offering a fast, secure, and interoperable solution that promotes financial inclusion and digital payments adoption.

Hence option C is correct.

USSD protocol is used for sending text messages and is similar to SMS

USSD, or Unstructured Supplementary Service Data, is a protocol widely used for sending text messages on mobile devices. It operates within the Global System for Mobile Communications (GSM) network, which is the prevalent standard for cellular networks globally. This protocol allows users to interact with various services and applications through text-based menus displayed on their mobile screens.

Similar to Short Message Service (SMS), USSD messages are composed of text, and they can be sent between a mobile device and an application server. However, there are distinct differences between the two. Unlike SMS, which stores messages and forwards them when the recipient's device is available, USSD operates in real-time. This means that USSD sessions are initiated and terminated instantly, providing immediate interaction between the user and the application.

USSD codes are often utilized for a variety of purposes, such as checking account balances, recharging prepaid mobile accounts, accessing mobile banking services, and more. Users simply enter a specific USSD code into their mobile phones' dialer, followed by the "send" button, to trigger a response from the corresponding service provider.

Hence option B is correct.