I do not see any answer choices, so I hope this helps.
Explanation:
This poem is about a crisis of faith. Science is taking over and therefore, it seems to be replacing "faith". The belief in the world of faith and religion is slipping away and it is going out like the tide does in the ocean/sea. I read up on this some more and found it interesting that Matthew Arnold literally was able to stand and look at the straits of Dover on the English Channel.
As time goes by. and water goes through the water cycle again and again. The amount of water on Earth stays the same. However one could argue with this due to global warming since our icebergs/glaciers are melting adding to sea-level rise.