Describe the role of Azure Key Vault in Azure SQL Database.

Azure Key Vault plays a crucial role in managing sensitive data, particularly in the context of Azure SQL Database. It is primarily designed to securely store and control access to secrets such as API keys, passwords, and cryptographic keys which are essential for encrypting data at rest and in transit. By centralizing the management of these keys and secrets, Azure Key Vault helps ensure that sensitive information is protected from unauthorized access while simplifying key management processes.

In the context of Azure SQL Database, this means that when data is encrypted, especially at the column or database level, the encryption keys can be securely managed and rotated using Azure Key Vault. This adds an extra layer of security to the database environment, helping organizations comply with regulatory requirements and best practices for data security.

The other options do not accurately capture the role of Azure Key Vault. While enhancing database performance, user management policies, and networking solutions are important aspects of database management, they are not functions served by Azure Key Vault. The vault's specific purpose is the management of sensitive information, making option B the most appropriate choice for describing its role within Azure SQL Database.