Which line from the text demonstrates an inverted syntax?
in the deserted, moon-blanch'd street,
how lonely rings the echo of my feet!
those windows, which i gaze at, frown,
silent and white, unopening down,

Here's an example of inverted syntax:
 Normal syntax: Jane ate a cake.
 Inverted syntax: A cake Jane ate.

I think that the second line probably has inverted syntax, since you can re-write it as shown below:
 Sentence given (inverted): How lonely rings the echo of my feet!
 Sentence re-ordered (normal): The echo of my feet rings lonely.

EDIT:
I think I made a mistake above ^
I believe its actually line three, which can be re-ordered to read: I gaze at those windows which frown

The answer is B. How lonely rings the echo of my feet! (hopes this helps)