rainnight

OG上的解释：Thus, an option that identifies some connection between

North and East Africa
which predates the tenth century would not support but rather undermine

the historians’
account。
其实本题的考点应该在于，如果证明NA和EA在10世纪以前就有贸易往来，那么就无

法证明“trade between North Africa and East Africa began at this period

(10 century)"。这是对应的D选项。
我不明白的是B选项，“The many surviving letters of pre-tenth-century

North African merchants include no mention of business transactions

involving East Africa." 这个选项并没有support结论的作用；但是和D相比，它

至少不会weaken the conclusion。