The correct answer is B. Trade and commerce
Explanation:
Early river civilization emerged as a result of the Neolithic revolution in which human groups stopped being nomads and instead settle as they implemented agriculture and herding. Besides this, as agriculture and herding increased there was more food and resources that the one human groups needed which is known as food surplus. This led to the first forms of trade and commerce between different groups or civilizations besides making river civilization grow and be more complex. According to this, complexity in early river civilization increased as did trade and commerce.
