I don't know his whereabouts.
A
His whereabouts are not known to me.
B
No one knows his whereabouts.
C
His whereabouts is not known by me.
D
His whereabouts had not been known to me.
Correct Answer: His whereabouts are not known to me.
His whereabouts are not known to me.Given sentence is in simple present tense and it is in active voice.
Rule :
Subject + (is/am/are) + V3 + Other agents