A user has launched an RDS postgreSQL DB with AWS. The user did not specify the maintenance window during creation. The user has configured RDS to update the DB instance type from micro to large. If the user wants to have it during the maintenance window, what will AWS do?

A. AWS will not allow to update the DB until the maintenance window is configured
B. AWS will select the default maintenance window if the user has not provided it
C. AWS will ask the user to specify the maintenance window during the update
D. It is not possible to change the DB size from micro to large with RDS