Which of the following defines 'authentication'?

Authentication refers to the process of confirming the identity of a person or system, ensuring that the communication or transaction is genuine and not fraudulent. In the context of electronic transactions, authentication primarily concerns validating the authenticity of messages or transmissions. This is crucial for maintaining the integrity and security of data exchanged, particularly in financial transactions where trust is paramount.

Choice B succinctly captures the essence of authentication as it highlights the importance of verifying that the messages received are indeed from the legitimate sender and have not been tampered with during transmission. This ensures that both parties in a transaction can trust the information being communicated, which is foundational in preventing fraud and unauthorized access.

The other options, while related to various aspects of transaction processes, do not encompass the true meaning of authentication in the context of transaction security. For instance, confidently verifying the transaction amount pertains to validation rather than authentication. Generating transaction receipts is more about record-keeping, and reviewing cardholder transaction history involves analysis rather than the process of proving identity or message authenticity. Therefore, the definition that focuses on validating the authenticity of communications is the most accurate representation of 'authentication' in this context.