Question

which of the following sentences is used in a passive voice?
A. the effects of cyanide are well known
B. They considered their options.
C. Having left the building, Elvis never returned.
D. I would not provoke that man if I were you

Answer 1

The correct answer would be sentenced C. Having left the building, Elvis never returned. 

Answer 2

The sentence used in the passive voice is A) The effects of cyanide are well known.
All other sentences are used in the active voice.