How can a Consultant ensure that Cases are closed when all Work Orders associated to the Case are complete?

Universal Containers (UC) wants to track the full lifecycle of their Cases. UC defines a Case as resolved when all interactions with the customer are complete .

How can a Consultant ensure that Cases are closed when all Work Orders associated to the Case are complete?
A . Use Workflow to close the Case when all Work Orders are closed.
B . Use Process Builder to close the Case when all Work Orders are closed.
C . Use Workflow to close the Case when the Work Order is dispatched.
D . Use Process Builder to close the Case when the Work Order is created.

Answer: B