5. why do many historians consider 3200 bce to be the beginning of history?
a. this was when first written language appeared.
b. this was when humans first discovered agriculture.
c. this was when the first humans inhabited the nile river.
d. this was when humans first discovered tools.

A. This was when the first written language appeared.

Explanation:

The term history is associated to the appearance of writing, therefore, prehistory refers to the period before (pre) writing existed.

In the case of 3200 BCE, it corresponds to the ancient civilization known as Mesopotamia.  There, a group called the Sumerians developed the world's first known writing system called cuneiform.  This was a pictographic system that was traditionally inscribed on clay tablets.

answer; (religion)

c) troops march forward in close formation against newer, more accurate weapons