Question

In this excerpt from "Dover Beach" by Matthew Arnold, which lines suggest that the speaker has undergone a loss of faith?

Answer 1

I believe the correct answer is B. But now I only hear its melancholy, long, withdrawing roar.
This line shows us a particular change in poet's heart - he used to think that the Sea of Faith was beautiful and mysterious, but now his opinion suddenly changed when he realized how melancholic it actually is. It suggests to us that he had a loss of faith.

Answer 2

Since the question asks for TWO answers (but doesn't say it here), they would be:

But now I only hear its melancholy, long, withdrawing roar,

and

And here we are as on a darkling plain swept with confused alarms of struggle and flight

@PLATONATION

hope this helps :)