Which of the following best describes the relationship between encryption and decryption?

The relationship between encryption and decryption can be best understood through the concepts outlined in the correct choice. Encryption is the process of converting readable data, often referred to as plaintext, into an unreadable format, known as ciphertext. This process is fundamental to securing information, as it ensures that only authorized individuals or systems can access the original data.

Decryption, on the other hand, is the reverse process. It takes the ciphertext and converts it back into plaintext, making the data understandable again for those who possess the proper decryption key or method. The distinction emphasizes that encryption and decryption are complementary processes.

In this context, the correct answer illustrates the direct relationship between the two processes: while encryption makes data unreadable, decryption restores its readability. This relationship is crucial for maintaining confidentiality and security in data communications and storage.