Question

the song dynasty promoted trade
across the gobi desert.
down the mekong river.
along the silk road.
on the great wall.

Explanation:

The Song Dynasty, while not controlling the traditional Silk Road routes in the northwest due to political circumstances, still had trade connections along the Silk Road (and maritime trade as well). The Gobi Desert trade was more associated with earlier dynasties or other groups; the Mekong River trade isn't a primary Song trade route; and the Great Wall was a defensive structure, not a trade route. So the correct option is the one about the Silk Road.

Answer:

C. along the Silk Road (assuming the options are labeled A, B, C, D with A: across the Gobi Desert, B: down the Mekong River, C: along the Silk Road, D: on the Great Wall)