In order to read a play properly, one must stage the play in one's own imagination.
a. true
b. false

It isn't necessary to stage a play in one's own imagination for one to be able to read the play properly. For that reason, I would say that the answer is False. 

Actors don't necessarily carry out plays in their imagination but rather just act it out, so the answer indeed would be false in this case. 

True