The question is for new users, answer A is not exact for that case.

i get confused, the question saids "NEW" users... if you apply this password policy it would affect all the users in the AWS account....

Because its mentioned "all new users"

You can set a custom password policy on your AWS account to specify complexity requirements and mandatory rotation periods for your IAM users' passwords. When you create or change a password policy, most of the password policy settings are enforced the next time your users change their passwords. However, some of the settings are enforced immediately. https://docs.aws.amazon.com/IAM/latest/UserGuide/id_credentials_passwords_account-policy.html#:~:text=Setting%20an%20account-,password%20policy,-for%20IAM%20users

To accomplish this, the solutions architect should set an overall password policy for the entire AWS account. This policy will apply to all IAM users in the account, including new users.

Set overall password policy ...

A is correct

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