What is designed to ensure that transmitted data across networks is not intercepted or understood by unintended recipients?

Encryption is the process that ensures transmitted data across networks is secured from interception or unauthorized understanding. By converting the original information into a coded format, encryption makes it unintelligible to anyone who does not possess the right decryption key. This is crucial in maintaining the confidentiality and integrity of sensitive information, especially in fields like healthcare, where patient data must be protected in compliance with regulations.

In contrast, virus protection focuses on safeguarding systems from malware and other malicious software, which is a different aspect of digital security. Physical barriers pertain to securing physical access to data centers or devices and do not directly address the issue of data transmission. User authentication involves verifying the identity of users accessing a system, which while important, does not encrypt the data being transmitted. Thus, encryption specifically targets the issue of keeping data private during transmission, making it the correct choice in this context.