Which of the following sentences is written in the passive voice?

AThey considered their options.
BThe effects of cyanide are well known.
CHaving left the building, Elvis never returned.
DI would not provoke that man if I were you.

Verified Answer :

passive is when something is done to the subject of the sentence by someone or something else. it formed by using the appropriate form of "are" + the third form of a verb.
so the answer should be B

B. The effects of cyanide are well known.