<Li> <P> The first turn of the Yangtze at Shigu (石 鼓) in Yunnan Province, where the river turns 180 degrees from south - to north - bound </P> </Li> <P> The first turn of the Yangtze at Shigu (石 鼓) in Yunnan Province, where the river turns 180 degrees from south - to north - bound </P> <Li> <P> The Jinsha River in Yunnan </P> </Li> <P> The Jinsha River in Yunnan </P>

Which of these would have most benefitted the economy of the song dynasty