AWS Organizations is the correct choice because it lets you programmatically create multiple AWS accounts and centralize billing so all costs roll up to a single payer account. It is built for multi account management and automation which matches the startup requirement to create 12 accounts quickly.

AWS Organizations provides APIs such as CreateAccount to automate provisioning and it supports consolidated billing under a payer account so costs aggregate in one place. It also enables governance features like service control policies to enforce policies across accounts while still allowing automated account creation and onboarding.

AWS CloudFormation is incorrect because CloudFormation orchestrates resources inside an existing account and does not natively create new AWS accounts, so it cannot meet the account provisioning requirement.

AWS IAM is incorrect because IAM manages users, roles, and permissions within a single account and it cannot be used to provision or manage multiple AWS accounts.

AWS Billing Conductor is incorrect because Billing Conductor helps customize billing views and perform chargebacks across accounts but it does not handle the creation or automated provisioning of AWS accounts.

Full AWS Practitioner Certification Question