Azure Key Vault is the correct answer. It is a secure store for storing various types of sensitive information, including passwords, certificates, API keys, and other secrets. Azure Key Vault provides secure access management and uses industry-standard algorithms, key lengths, and hardware security modules (HSMs) to safeguard secrets and keys. Other options, such as Azure Security Center, Azure Storage account, and Azure Information Protection, are not specifically designed for storing and managing sensitive information like certificates.