正解:D
Symmetric encryption is a type of encryption that uses the same key to encrypt and decrypt data. Asymmetric encryption is a type of encryption that uses a pair of keys: a public key and a private key. The public key can be used to encrypt data, but only the private key can decrypt it, and vice versa. An advantage of symmetric encryption over asymmetric encryption is that it is faster and more efficient for encrypting large amounts of data, such as in sessions or bulk transfers. Asymmetric encryption is slower and more computationally intensive, but it is more secure and suitable for key exchange or digital signatures. Reference:= Cisco Cybersecurity Operations Fundamentals, Module 2: Security Monitoring, Lesson 2.3: Cryptography and PKI, Topic 2.3.1: Cryptography