The correct answer is indeed C) the outbreak of the plague. Actors were forced to resume their travels because of the plage since the authorities had closed the theaters were they used to perform, due to this they didn't have a way to make a living, so they return to their caravans as he used to do before in order to survive and keep on having a job.
The other options are entirely incorrect because A) The population was quite big in London so that could not be a reason to leave. B) Popularity was never mentioned as part of this excerpt, D) There was never mention a ban against them in Stratford upon Avon.
Answer: To help slow down the spread of the virus
Explanation:
It's a great way to promote business, get people to find put about your business, earn tons of money, etcetera.
It gives the sense that time is moving quickly and thus creates excitement.