How should the app builder configure the Invoice Number field?

Universal Containers has a new custom object for Invoices that includes an Invoice Number field, Before the Invoice object can be used, invoices will be migrated from an external system maintaining their current Invoice Number. After the migration, salesforce will be the system of record and each new Invoice created in Salesforce must have a unique Invoice Number.

How should the app builder configure the Invoice Number field?
A . Create a Text filed for the original Invoice Number and an AutoNumber field for the Salesforce Invoice Number.
B . Create a Text field and mark it as a unique external ID field.
C . Create a Text field, then change it to AutoNumber after the migration.
D . Create an AutoNumber field and migrate the Invoices

Answer: B

Explanation:

The Invoice Number field should be a Text field and marked as a unique external ID field. This will allow the migration of invoices from an external system while maintaining their original Invoice Number. It will also ensure that each new Invoice created in Salesforce has a unique Invoice Number.