How can you ensure redundant power to the rack?

You are installing a rack at customer site.

How can you ensure redundant power to the rack?
A . Install two power distribution units (PDUs) with each one connected to a power socket supplied by an independent electrical power source.
B . Ensure 3-phase power is available in the data center.
C . Connect an uninterruptible power supply (UPS) to redundant circuit breakers at the facility power source.
D . Use two different power cords to connect the server to the power grid at the customer site.

Answer: C