Read this excerpt from "A Servant to Servants" and answer the question.
There's nothing but a voice-like left inside
That seems to tell me how I ought to feel,
And would feel if I wasn't all gone wrong.
You take the lake. I look and look at it.
I see it's a fair, pretty sheet of water.
I stand and make myself repeat out loud
The advantages it has, so long and narrow,
Like a deep piece of some old running river
Cut short off at both ends.
Based on the narrator's emotional state, what is most likely the meaning of sheet?
O a thin surface layer
a flat, open expanse
O an insulating cover
O a blank rectangular area