Which method is used to convert information into a code to prevent unauthorized access?

The method used to convert information into a code to prevent unauthorized access is encryption. This process involves transforming plain text data into a coded format, which can only be read or decrypted by someone who possesses the appropriate key or password. The primary goal of encryption is to protect sensitive information from being accessed by unauthorized parties, ensuring confidentiality, integrity, and security of data during transmission or while stored.

Encryption can be applied to various types of data, such as messages, files, or entire databases. By encoding the data, encryption safeguards against eavesdropping, data breaches, and other cyber threats. This makes it a fundamental practice in fields requiring stringent data protection, like finance, healthcare, and communications.

In contrast, caching refers to the temporary storage of data to improve retrieval times, data mining involves analyzing large datasets to uncover patterns, and normalization is a process used in databases to minimize redundancy and dependency. None of these methods are aimed at securing data through coding, which clearly differentiates encryption as the correct answer in this context.