Successive Sultans attempted to control their nobility in different ways, though not with much success

Q. Successive Sultans attempted to control their nobility in different ways, though not with much success. Examine the following statements:

1. Balban created nobility based on racial antecedents
2. Ala-ud-din Khilji built nobility based on personal loyalty checked by spies
3. Mohammed bin Tughlaq dispersed the nobility for better control
4. Firoz Shah Tughlaq built a small nobility on the principle of heredity
   Select the code for correct statements:
   (a) Only 1, 3
   (b) Only 2
   (c) Only 3 and 4
   (d) 1, 2, 3 and 4
   Ans: (d) 1, 2, 3 and 4