Which feature of this map would best the reader understand its purpose? 1 2 3 4

2

Because it tells the reader what there is to the map even though the title tells me what the map is about but the key shows me that they're trading

3 and 4 shows me direction and distance which i don't really need to know to understand this map unless we are going into depth with it

Option (2)

Explanation:

The given map shows the river valley civilization and is marked by 1 and is highlighted at the apex portion of the map.

Feature 2 that is marked in the left bottom of the map describes how the trading between the different places is taking place, and colors that are used in the location best highlights the different places and their trading route is shown by the red line containing arrows on both the ends. This feature is often known as the map index (legend) that best explains the things that are provided in the map.

Feature 3 and 4 that are marked on the right of the map show the North-South direction and map scale respectively.

Thus, feature 2 is primarily helpful in understanding the map.

Hence, the correct answer is option (2).

81 is a composite number.