4 Answers
This example enables IAM policies. This means that if this is in place as part of your key’s policy, you can then use IAM policies to give IAM users and roles in the account access to the CMK (A). By default it also enables the root user of account 111122223333 access (C).
Best answer is:
A and C
Check out the following documentation which should help you work out the answer!
https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_elements_principal.html
https://docs.aws.amazon.com/kms/latest/developerguide/key-policies.html
I really like this re:Invent 2017 video: https://www.youtube.com/watch?v=X1eZjXQ55ec
Explanation of this policy begins at 22:56. Delegates all KMS actions to IAM.