The correct option is D The eldest member of the family.
The reign of the Perumals came to an end by the 12th century. Consequently, the chieftains, who were the local rulers under the Perumals, began to rule their respective Nadus independently.
The region under the control of a chieftain was known as Swaroopam. The joint family of the chieftain was also known as Swaroopam. The eldest member of the family became the ruler. There were disparities in wealth and military power among the Nadus and the chieftains fought among themselves for power.