Which of the following is primarily related to the management of cryptographic keys?

The selection of key management as the correct answer is based on its central role in establishing and maintaining the security of cryptographic systems. Key management encompasses the processes and techniques used to manage cryptographic keys throughout their lifecycle, including their generation, storage, distribution, rotation, and destruction. Proper key management is essential to ensure that keys remain confidential and secure, which directly affects the integrity and confidentiality of encrypted data.

In contrast, data encryption refers specifically to the method of converting plaintext into ciphertext using an algorithm and a key. While encryption is vital for data protection, it does not encompass the broader aspects of key management needed to safeguard the keys themselves. Data compression involves reducing the size of data for storage or transmission, which is unrelated to cryptography. Data transmission involves the transfer of data between systems, and while it may use encryption to secure the data in transit, it does not address the management of the cryptographic keys.

Therefore, key management is indeed the primary concern when it comes to managing cryptographic keys, making it the most appropriate choice.