Correct Answer: (d) Firuz Tughluq set up a separate department of slaves
Solution:(1) Balban established an army department 'Diwan-e-Arz to look after a large standing army with a view to potential Mongol threats. He made Imad-ul-Mulk his commander who was very honest and hardworking. Balban freed him from financial control of Wazir to ensure him financial autonomy. The credit of good arrangement of Balban's army goes to Imad-ul-Mulk. (ii) The branding system of horses was introduced by Alauddin, not by Balban. (iii) Firuz Tughluq, the cousin brother of Muhammad-Bin-Tughluq, sat on the throne after him (1351-1388 A.D.). (iv) Firuz Shah Tughluq had established a separate department 'Diwan-e-Bandgan' of slaves. Firuz Shah Tughluq was fond of slaves. Thus, option (d) is the correct answer.