What combines symmetric cryptography with hashing?

The correct answer is HMAC, which stands for Hash-based Message Authentication Code. HMAC combines the use of a cryptographic hash function with a symmetric key to provide both data integrity and authentication.

Here's how it works: HMAC first takes a message and a secret symmetric key. It processes these through a hash function to produce a fixed-size output known as the HMAC. This output is unique to both the message and the key, meaning that any modification to the message or the use of a different key will produce a different HMAC. This characteristic allows HMAC to ensure that the data has not been altered in transit and verifies the authenticity of the sender who possesses the key.

The other options refer to similar concepts but do not have the same established significance or usage as HMAC. For instance, while BMAC, CMAC, and AMAC may refer to different variations or methodologies involving message authentication and integrity, they are not as widely recognized or utilized in practice when compared to HMAC. HMAC's design leverages proven cryptographic principles and has become a standard approach in secure communications, making it the most effective choice that blends symmetric cryptography with hashing for securing data.