A company wants to build a scalable key management infrastructure to support developers who need to encrypt data in their applications. What should a solutions architect do to reduce the operational burden?

1. Use multi-factor authentication (MFA) to protect the encryption keys.
2. Use AWS Key Management Service (AWS KMS) to protect the encryption keys.
3. Use AWS Certificate Manager (ACM) to create, store, and assign the encryption keys.
4. Use an IAM policy to limit the scope of users who have access permissions to protect the encryption keys.