Explanation:

Varna System arose in North India and later prevailed in all over the country. The foriegners who came to India in ancient times were absorbed in one category or the other. It affected the Christans as well as Muslims too, because the people who converted from Hinduism to these religions, continued to maintain some of their old practices. Therefore, option 1 is correct. 

Belan Valley which is located in North Vindhyas, comprise of evidences from all three phases of stone age i.e Paleolithic, Mesolithic and Neolithic. Therefore option 2 is incorrect.

Some people in South India buried tools, weapons, pottery and other belongings in the graves which were encircled by big pieces of stone. These structures are called Megaliths. So, it was a practice peculier to South India. Therefore, option 3 is incorrect.

Ancient coins were made of copper, silver, gold, led as well as burnt clay. They were not solely made of led. Therefore option 4 is incorrect.