A sudden increase in the production of elephant ivory artifacts on the Mediterranean coast of North Africa
occurred in the tenth century. Historians explain this increase as the result of an area opening up as a new
source of ivory and argue on this basis that the important medieval trade between North Africa and East Africa
began at this period.

Each of the following, if true, provides some support for the historians' account described above EXCEPT:

(A) In East Africa gold coins from Mediterranean North Africa have been found at a tenth-century site but at no earlier sites.  Trade began in 10th century. Strengthens - Hence incorrect

(B) The many surviving letters of pre-tenth-century North African merchants include no mention of business
transactions involving East Africa. -> trade did not start before 10th century - Strengthens - Hence incorrect

(C) Excavations in East Africa reveal a tenth-century change in architectural style to reflect North African
patterns. -> reveals a 10th Century CHANGE -> means trade started in 10th century. Strengthens - Hence incorrect

(D) Documents from Mediterranean Europe and North Africa that date back earlier than the tenth century
show knowledge of East African animals. -> as documents were dated back earlier than 10th century, it implies that there were trades or connection between North Africa and East Africa BEFORE 10th century. Does not support the conclusion - Hence our required ans. Remember this is an EXCEPT question

(E) East African carvings in a style characteristic of the tenth century depict seagoing vessels very different
from those used by local sailors but of a type common in the Mediterranean. -> read the keyword "vessels very different from those used by local sailors but of a type common in the Mediterranean" carefully. It means the vessels were from Mediterranean( North Africa). Hence trade was there in 10th century. It also supports. Incorrect

Thanks,
Sam