Explanation
Removing the Work Order Edit permission from the sales representative profile is the optimal approach to implement these requirements, as it will prevent sales representatives from changing virtual container work orders that are provisioned immediately by the system. Option B is incorrect, since removing the edit button from the work order page layout would not prevent sales representatives from editing work orders using other methods, such as inline editing or data loader. Option C is incorrect, since changing the record type/page layout assignment for Work Order to be Read Only would not affect the edit permission, but only the layout configuration. Option D is incorrect, since implementing a sharing rule that changes access for all Work Order to Read would not prevent sales representatives from editing work orders that they own.

Explanation
Creating a specific Sharing Reason for the custom object is the best way to make sure that users that gained access to a custom object do not lose access to it when its owner is changed. Sharing Reasons are labels that identify why users or groups have access to records. They are used in Apex managed sharing, which allows developers to programmatically create and maintain sharing rules1. Using ''runAS'' system method in Apex classes to enforce record visibility, creating a new record in_Share object with RowCause ''Manual'', and using ''With Sharing'' keyword to make sure record visibility will be considered are not ways to prevent losing access when the owner changes.