题目选项分析

Unlike other Mayan cities, Cancun seemed to be using its strategic position at the foot of the highlands, which was a source of jade, obsidian, and other valuable commodities, in becoming a commercial power throughout the lowlands.

Unlike other Mayan cities, Cancun seems to have used its strategic position at the foot of the highlands, a source of jade, obsidian, and other valuable commodities, to become a commercial power throughout the lowlands.