The correct options are
A It was used to reward bave war heroes who were loyal to the throne.
B The King could expect a steady flow of revenue from the Nayankaras.
C Nayankaras were given to rebellious chiefs as well to quell them.
Rudramadevi and Prataparudra took help from skilled warriors from families that were not very powerful, but who were loyal to the throne by giving them the title of 'Nayaka'. Each nayaka had to maintain a stipulated amount of army, from the income they derived from the nayankara, for the service of the king. They were also used to subdue the rebellious chiefs. This arrangement was called Nayankara system.