If each department within a company has its own AWS account, what is one way to enable consolidated billing?

If each department within a company has its own AWS account, what is one way to enable consolidated billing?
A . Use AWS Budgets on each account to pay only to budget.
B . Contact AWS Support for a monthly bill.
C . Create an AWS Organization from the payer account and invite the other accounts to join.
D . Put all invoices into one Amazon Simple Storage Service (Amazon S3) bucket, load data into Amazon Redshift, and then run a billing report.

Answer: C