Northern Trail Outfitters is migrating from a legacy emailing tool to Marketing Cloud. As part of the migration, they have to go through a security review. Their data privacy team has made it clear that the data in the sandbox should never be mixed with data In production during testing cycles. What recommendation would a consultant provide on the architecture to fulfill this requirement?

A. Implement two separate Marketing Cloud instances.

B. Ensure test sends are done from data extensions with attribute 'Is Testing1.

C. Create one or more additional business units for testing.

D. Use Subscriber Filter per business unit to filter production from test data