The rime of the ancient Mariner is a ballad stanza and the rest are blank verse
If you want an explanation:
A blank verse doesn’t rhyme and a ballad does
This is a personal question for YOU. So, I suggest YOU complete it yourself. It's your own experience! Have a nice day.
The sentence that has the correct subject- verb agreement is the following one: Neither the Western Hemisphere nor the Eastern Hemisphere are immune to flooding.
The verb "to be" can't be singular because the writer mentions the two hemispheres (the Western Hemisphere and the Eastern one). That is why the first option is the correct one.
