Which of the following cryptographic solutions protects data at rest?

Full disk encryption (FDE) protects data at rest by encrypting all data on a storage device, such as a hard drive, making it unreadable without the correct decryption key. This is crucial for securing sensitive information on lost or stolen devices. Digital signatures provide data integrity and authentication, not data at rest protection. A private key is a component of asymmetric cryptography used for encryption or digital signatures, not a standalone solution for data at rest. Steganography hides the existence of data within other data, but doesn't inherently encrypt or protect the original data at rest from unauthorized access if discovered.