“I'm not saying I'm gonna change the world, but I guarantee that I will spark the brain that will change the world.” That was a quote by Tupac Shakur, a poet, and an inspiration. What does it mean to 'change the world'? Changing the world is the most politically correct term to use, as its literal meaning is the same as its metaphorical one, so there's no confusion. Just by being on Earth, at any given moment, and doing something or even nothing we are already changing the world.
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.
A is the answer hope this helps