I reckon everything but E is a correct answer.
This part of the excerpt seems to be correct as it reveals that the diet alone is responsible for his ninth birthday: "It had plenty of room to expand, thanks to the spare diet of the establishment; and perhaps to this circumstance may be attributed his having any ninth birth-day at all."
Answer:to clearly communicate expectations
Explanation:
Polonius is using his daughter to spy her conversation with Hamlet. He teaches how to act naturally, how to walk and pretend that she is reading.
In that last phrase, he is saying that we humans often act in deceitful ways, for which we are to blame.
He admits that he is making a mistake, in teaching that kind of behaviour to his own daughter.