One of the main reasons why primary sources are valuable to historians is because "<span>They give insight into the thoughts and feelings of a participant in history," since these are sources that originated during the time in question, and are "unaltered". </span>
I believe it’s D ! I did some research and D seems like the only logical answer.
It helped solve the problems that were not directly said or pointed out in the constitution
From my knowledge, the Huang River is the birthplace of civilization in China. In fact, some of the most ancient settlements in Eastern Asia is situated on the banks of the Huang River. There is a Chinese cliché that says that "the Huang River is the cradle of the Chinese". Now to answer your question, the river provided a source of food and transportation, which encouraged early barter exchange throughout the small villages/tribes of ancient China.
