What does a blinking red power button indicate on an HP Z series workstation?

What does a blinking red power button indicate on an HP Z series workstation?

A.
The computer is in sleep mode

B.
The computer is turned on

C.
The power supply is in an error state

D.
The computer is in an error state

Explanation:
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.oid=3718668&ac.admitted=1389265033333.876444892.492883150