Which of the following is an extremely valuable source for the history of the reign of Sultan Muhammad Bin Tughluq and Sultan Firuz Shah, in the form of letters and official documents?
[A] Tughluknama
[B] Qiran-us-Sadin
[C] Insha-I-Mahru
[D] Tarikh-i-Firozshahi
Correct Answer: C [Insha-I-Mahru]