You have an Opswork stack setup in AWS. You want to install some updates to the Linux instances in the stack. Which of the following can be used to publish those updates? Choose 2 answers from the options given below.

Answer options:

A.Create and start new instances programmatically to replace your current online instances. Then delete the current instances.
B.Use Auto-scaling to launch new instances and then delete the older instances.
C.On Linux-based instances in Chef 11.10 or older stacks, run the Update Dependencies stack command.
D.Delete the stack and create a new stack with the instances and their relevant updates.

Answer - A and C
As per AWS documentation,
By default, AWS OpsWorks Stacks automatically installs the latest updates during setup, after an instance finishes booting. AWS OpsWorks Stacks does not automatically install updates after an instance is online, to avoid interruptions such as restarting application servers. Instead, you manage updates to your online instances yourself. So you can minimize any disruptions.
We recommend that you use one of the following to update your online instances.
Create and start new instances to replace your current online instances. Then delete the current instances.
The new instances will have the latest set of security patches installed during setup.
On Linux-based instances in Chef 11.10 or older stacks, run the Update Dependencies stack command, which installs the current set of security patches and other updates on the specified instances.
More information is available at:
https://docs.aws.amazon.com/opsworks/latest/userguide/workingsecurity-updates.html