Who were the 'Nayakas' in the Vijayanagara Empire?

Military chiefs

The correct answer is Option (4) → Military chiefs

The nayakas were the 'Military Chiefs' of the Vijayanagara Empire

Krishnadeva Raya’s rule was characterised by expansion and consolidation. This was the time when the land between the Tungabhadra and Krishna rivers (the Raichur doab) was acquired (1512), the rulers of Orissa were subdued (1514) and severe defeats were inflicted on the Sultan of Bijapur (1520). Although the kingdom remained in a constant state of military preparedness, it flourished under conditions of unparalleled peace and prosperity. Krishnadeva Raya is credited with building some fine temples and adding impressive gopurams to many important south Indian temples. He also founded a suburban township near Vijayanagara called Nagalapuram after his mother. Some of the most detailed descriptions of Vijayanagara come from his time or just after. Strain began to show within the imperial structure following Krishnadeva Raya’s death in 1529. His successors were troubled by rebellious nayakas or military chiefs. By 1542 control at the centre had shifted to another ruling lineage, that of the Aravidu, which remained in power till the end of the seventeenth century. During this period, as indeed earlier, the military ambitions of the rulers of Vijayanagara as well as those of the Deccan Sultanates resulted in shifting alignments.