【正确答案】 A

【答案解析】[精解] 本题是一个细节题。选项中的细节定位分布在全文。但是主题问题中时间只有在第一段提到。所以考生可以很快根据时间找到定位而不用到全文去找。回到原文：“By the early eleventh century，however，the empire had regained almost half of its lost possessions，its new frontiers were secure，and its influence extended far beyond its borders．The economy had recovered，the treasury was full，and art and scholarship had advanced．”。只要在选项中找到概括合适的选项即可。
A．赶走了保加利亚的军队。正确，和文中的“the empire had regained almost half of its lost possessions，its new frontiers were secure”意思吻合。
B．具有和罗马和奥古斯都的军队一样规模的军队。错误，文章中没有提到，虽然和原文的意思没有冲突。
C．足够强大来抵抗哈里发阿拉伯国家的军事力量。错误，该选项的定位在文章的最后一段“in the 860's the Byzantine Empire began to recover from Arab incursions so that by 872 the military balance with the Abbasid Caliphate had been permanently altered in the empire's favor．”。可见选项的时间错误。
D．掌握了拜占庭政权。错误，文章中没有对应的原文。