A. Use an Apex Trigger to change the Account field value from "prospect" to "customer" and email the Account Owner as a reminder to get an approval from their Manager.

B. Use a Record Trigger Flow to change the Account field value from "prospect" to "customer" and email the Account Owner.

C. Use o Process to monitor t changed field value on the Account object from "prospect" to "customer" and an action to submit the record to an Approval Process

D. Use a Flow to update the field and trigger on Approval Process to notify the VP of Sales.