Feroz Tughlaq's most defective military reform was introducing the hereditary system in the army. When army positions became hereditary (passed from father to son), it destroyed merit-based recruitment, led to declining quality of soldiers over generations, and created a class of soldiers who were more interested in their privileges than in military effectiveness. The Jagir-based army (options A and B) was also problematic, but the hereditary system fundamentally undermined the army's professionalism and effectiveness.