The statement is - a. True.
Throughout the human history, before the modern age, people were not able to pass great distances or pass certain natural obstacles. This meant that different groups of people that were separated by some big natural barrier where not able to communicate between each other, or the communication was very rare and limited. That resulted in the formation of different cultures, unique, evolved totally independently from one another. There's multiple examples of this, like the Arabian culture which was isolated because of the vast deserts, the Aboriginal culture in Australia which was isolated because of the large water bodies, the Eskimos in North America that were isolated because of the harsh Arctic conditions etc.
