A new Vault administrator is writing a CURL command (shown below) to retrieve a secret...

Comprehensive and Detailed in Depth Explanation:

The error occurs because the CURL command uses the wrong endpoint for a KV v2 secrets engine. The HashiCorp Vault documentation states: "The KVv2 store uses a prefixed API, which is different from the version 1 API. Writing and reading versions are prefixed with the data/ path." For KV v2, the correct endpoint to retrieve a secret is /v1/secret/data/audio/soundbooth, not /v1/secret/audio/soundbooth, which applies to KV v1.

The docs explain: "In KV v2, the data/ prefix is required when accessing secrets via the API to distinguish data operations from metadata or versioning tasks." Option A (VAULT_ADDR) is irrelevant for API calls, as it’s CLI-specific. Option C (token UI restriction) is incorrect—tokens apply universally. Option D misinterprets v1 as the API version, not the engine version. Thus, B is correct.