Why did even the people in the prehistoric period live in a community ?

Prehistory, also known as pre-literary history,[1] is the period of human history between the use of the first stone tools by hominins c. 3.3 million years ago and the invention of writing systems. The use of symbols, marks, and images appears very early among humans, but the earliest known writing systems appeared c. 5,300 years ago and it took thousands of years for writing systems to be widely adopted. In some human cultures, writing systems were not used until the nineteenth century and, in a few, not even until the present. The end of prehistory therefore came at very different dates in different places, and the term is less often used in discussing societies where prehistory ended relatively recently.

answer; i believe the correct answer is (a) the correlation between the cause variable and outcome variable is zero;

answer; i believe its (transgender);