An uninterrupted power supply (UPS) can be online or standby. Which of the following is a true statement about one of these types?

A.
Online UPS systems use DC line voltage to charge a bank of batteries.

B.
Online UPS has an inverter that changes the AC output from the batteries into the required DC form and that regulates the voltage as it powers computer devices.

C.
Standby UPS devices stay active until a power line fails.

D.
Standby UPS has sensors that detect a power failure, and the load is switched to the battery pack.

Explanation:
A UPS can be online or standby. Online UPS systems use AC line voltage
to charge a bank of batteries. When in use, the UPS has an inverter that changes the
DC output from the batteries into the required AC form and that regulates the
voltage as it powers computer devices. Standby UPS devices stay inactive until a
power line fails. The system has sensors that detect a power failure, and the load
is switched to the battery pack.