Correct Answer: (a) Both (A) and (R) is true, and (R) is the correct explanation of (A).
Note: During the reign of Akbar, for every ten cavalrymen, the Mansabdars had to maintain twenty horses. The main reason for this custom was that it was essential to give rest to the horses during the long journey and it was needed to replace horses during the war. Thus, Assertion (A) and Reason (R) both are correct, and Reason (R) is the correct explanation of Assertion (A).