How does an inline UPS protect computer equipment against electrical power brownouts and blackouts?

How does an inline UPS protect computer equipment against electrical power brownouts and blackouts?

• by grounding excess electrical voltage
• by using a battery to supply a constant level of voltage
• by switching from main power to a standby power source
• by stopping the flow of voltage to the computer
  

  Explanation: Uninterruptible power supplies (UPS) contain a battery which is constantly providing a consistent level of voltage to the computer.