Keyes because keys plural is just an s and not an es
If I'm correct its C hope that helps:)
Homes on East Egg are wealthy from long lines of generations (a son will inherit his father's fortune), whilst homes on West Egg are people who built up their fortunes (ex. people who gain money from working in industries).
I'm pretty sure it's A or B but I'm not sure exactly which one it is
No it is not. It is an adverb phrase since it lacks a subordinating conjunction.
Adverb clauses must be preceded or started by a subordinating conjunction such as after, if, because or although. For a sentence to qualify as an adverb clause it must include in its body a subject and a verb.
As a general rule you can use the following formula:
An adverb clause equals a subordinate conjunction plus a subject plus a verb, and it should be answering how? when? where? or why?