How can the system admin ensure that the instance does not get terminated?

An organization has setup Auto Scaling with ELB. Due to some manual error, one of the instances
got
rebooted. Thus, it failed the Auto Scaling health check. Auto Scaling has marked it for
replacement. How can the system admin ensure that the instance does not get terminated?

A.
Update the Auto Scaling group to ignore the instance reboot event

B.
It is not possible to change the status once it is marked for replacement

C.
Manually add that instance to the Auto Scaling group after reboot to avoid replacement

D.
Change the health of the instance to healthy using the Auto Scaling commands

Explanation:
After an instance has been marked unhealthy by Auto Scaling, as a result of an Amazon EC2 or
ELB health check, it is almost immediately scheduled for replacement as it will never automatically
recover its health. If the user knows that the instance is healthy then he can manually call the
SetInstanceHealth action (or the as-setinstance- health command from CLI. to set the instance’s
health status back to healthy. Auto Scaling will throw an error if the instance is already terminating
or else it will mark it healthy.