The suggested answer is A.
The biggest concern with hosting a key management system outside of the cloud environment is confidentiality. A key management system is used to securely store and manage keys, which are crucial for encrypting and decrypting data. If this system is outside the cloud environment, it may be more exposed to potential unauthorized access, leading to a compromise of the keys' confidentiality. This exposure increases the risk of the sensitive data being accessed by unauthorized parties, making confidentiality the primary concern.