In Nebraska, this Google Maps aerial planimetric (Links to an external site.) (looking straight down) view, you are looking at the drainage basin of Cub Creek. All of the different tributaries flow into the scenic Niobrara River. What is the best answer for the pattern of this drainage basin?

The drainage basin of the Niobara River is dendritic.

Explanation:

The name dendritic comes from having the shape of the branches of a tree.

The Niobara River is like the trunk, and the tributaries are the little branches that stem from it.

Looking at a map of Nebraska on Google Maps, it can be seen that this dendritic pattern is repeated the Northeast of the state, to the Westernmost part of it.

81 is a composite number.