Here it is very important to understand the timeline of the happenings. If I understand this rigth, then first there was the great debate untile some Schliemann discovered a site and this discovery
has validatet (until today) ... so at the end, we need present perfect. At the beginning we need past perfect and in the middle the simple past. Only D fulfils this. Do not really have to look after the other errors. However, the constructions I do not like in the other sentences are marked
yellow.There
was great debate among Greek historians whether the city of Troy ever existed or it was a figment of fiction, until the noted archaeologist Schliemann discovered in Turkey a site that many believe to be the ancient city of Troy, a discovery that validated its historical importance along with its literary eminence hitherto
A. was great debate among Greek historians whether the city of Troy ever existed or
it was a figment of fiction, until the noted archaeologist Schliemann discovered in Turkey a site that many believe to be the ancient city of Troy, a discovery that validated
(wrong tenses, we need a present perfect at the end, it is still valid today)B. had been great debate among Greek historians whether the city of Troy ever existed or was a figment of fiction, until the noted archaeologist Schliemann discovered in Turkey a site that many believe to be the ancient city of Troy, a discovery that validated
(wrong tenses, we need a present perfect at the end, it is still valid today)C. was great debate among Greek historians whether the city of Troy ever existed or
it was a figment of fiction, until the noted archaeologist Schliemann discovered in Turkey a site that many believe to be the ancient city of Troy, a discovery that had validated
(wrong tenses, we need a present perfect at the end, it is still valid today)D. had been great debate among Greek historians whether the city of Troy had ever existed or had been a figment of fiction, until the noted archaeologist Schliemann discovered in Turkey a site that many believe to be the ancient city of Troy, a discovery that has validated,
correct tensesE. had been great debate among Greek historians whether the city of Troy ever existed or
it was a figment of fiction, until the noted archaeologist Schliemann discovered in Turkey a site that many believe to be the ancient city of Troy, a discovery that validates
(wrong tenses, we need a present perfect at the end)