GMAT Sentence Correction (SC) | Re: Although Ghana is a relatively small country

Can an adjective modify another adjective?
IMO an adverb should modify an adjective....
agrarian based is a adjective....modifying the economies....and former is an adjective...which is correct...
Therefore formerly is correct and former is incorrect...so option B C D are out
among A and E ...A is better...in E comma are not needed..

Expert please comment on my undertsanding

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