With reference to the Amaranayakas system of Vijayanagara, consider the following statements:

a. The Amara-nayakas were military commanders who were given territories to govern by the Raya.

b. They retained part of the revenue for personal use and for maintaining a stipulated contingent of horses and elephants.

c. The Amara-nayakas sent tribute to the king annually and personally appeared in the royal court with gifts to express their loyalty.

Which of the statements given above are correct?