What must you ask the customer for before a test drive?

Answer: C — Their driver license

Asking a customer for their driver's license is necessary before a test drive because it verifies their identity, age (if required), and driving eligibility. Options A and B may also be required, but not as crucial as the driver's license for a test drive. Option D is not relevant to a test drive and is considered personal and confidential information, so it should not be requested from a customer.