Comprehensive and Detailed In-Depth Explanation:

Vault allows key export under specific conditions:

A. Yes, if Exportable: "When creating the key, the exportable flag must be set as true. By default, it is false." If set, "this enables the keys to be exportable," allowing retrieval for external storage. "Once set, this cannot be disabled."

Incorrect Option:

B. No: Incorrect if the key is exportable. "You cannot export the encryption key from Vault if it was not configured to be exportable."

This feature, while not best practice, supports disaster recovery scenarios.