Nation states are difficult to create because of colonies ((tell me if u need to know why because I can help with that))
D. single- and simple multi-celled organisms
Although more complex animals like invertebrates and multi-celled organisms began to appear, it was very late compared to the original, simpler organisms for which the Precambrian time is characterized by.
If you're referring to streams/rivers of water that run independently of another source in the ocean these are referred to as "currents" and can be very powerful depending on their location.
Answer:
B sorry that I said D first
Explanation:
