Answer:
A.) The rise of kingdoms because of the importance of controlling land and long distance travel routes
Step-by-step explanation:
I was going to say D.), but I think that answer A.) is more correct.
In the Vedic age, many different items such as jewelry, pottery and weaving were traded during this time, along with other materials. Not only that, but during this time the discovery of steeling iron was found, which led to taking the place of using bronze for things such as weapons. Iron was heated to a very high level, then molded and cooled.
But because of all of this and more, the trades were unfair, most of them trades with no money in return for those giving their makings to the people who wanted them. In the end, this trading system led to be corrupt, in the sense that things were not fair between the trades that went on.
Let me know if you have any more questions, I hope that this helps.