Which measure should a company implement to improve security for its AWS account?

Requiring multi-factor authentication (MFA) for privileged users significantly enhances security by adding an extra layer of verification beyond just a password, making it much harder for unauthorized individuals to access the account even if they compromise credentials. Removing the root user account is not possible, as it's a permanent and essential account for certain operations. Creating an access key for the AWS account root user is a security risk, as root user access keys grant unrestricted permissions and should generally be avoided; programmatic access should use IAM users with specific permissions. Creating an access key for each privileged user is acceptable for programmatic access, but it doesn't address interactive login security as effectively as MFA, and MFA should still be used in conjunction with access keys for privileged users where applicable.