An Organization Has Hosted an Application on the EC2 Instances

Multiple Choice

An organization has hosted an application on the EC2 instances. There will be multiple users connecting to the instance for setup and configuration of application. The organization is planning to implement certain security best practices. Which of the below mentioned pointers will not help the organization achieve better security arrangement?

A) Allow only IAM users to connect with the EC2 instances with their own secret access key.
B) Create a procedure to revoke the access rights of the individual user when they are not required to connect to EC2 instance anymore for the purpose of application configuration.
C) Apply the latest patch of OS and always keep it updated.
D) Disable the password based login for all the users. All the users should use their own keys to connect with the instance securely.