Which of the following is NOT a use case for Vault?

The correct choice is based on the understanding of HashiCorp Vault's primary functions and use cases. Vault is designed to manage secrets and protect sensitive data, primarily focusing on secure storage, encryption capabilities, identity management, and key management.

Data encryption involves the use of Vault to encrypt data at rest and in transit, leveraging its encryption as a service feature. Identity-based access allows for fine-grained permissions and access controls by integrating with identity providers and managing user authentication. Key management is a core function of Vault, which provides features for managing and rotating cryptographic keys.

User account recovery, on the other hand, is generally not considered a key use case for Vault. It pertains more to user lifecycle management and identity management systems rather than the secret management and encryption functionalities that Vault is primarily built to serve.

Therefore, C is the answer that does not align with the fundamental use cases of Vault.