To increase the supply of food, some neolithic communities living in arid regions of the world devloped

Irrigation systems

Explanation:

Neolithic comes after Paleolithic Period,and it preceded the Bronze Age. It can also be regarded as

"New Stone Age" which is known as

stage towards final cultural evolution as well as technological development that exist between prehistoric humans. The first Neolithic communities were recorded to have lived in densely built settlements. They are usually between the number of 50 up to 300 individuals. It should be noted that to increase the supply of food, some neolithic communities living in arid regions of the world developed Irrigation systems

the answer is c. many americans held nativist or racist views