Ziauddin Barani’s Tarikh-i-Firoz Shahi is the most authoritative contemporary source for Balban’s “Blood and Iron” policy. It provides detailed accounts of his strict administration, elimination of the Chahalgani, suppression of rebellions and establishment of harsh court rituals. Earlier sources like Tabaqat-i-Nasiri end before Balban’s formal reign and cannot fully describe these policies. ANSWER: (B) Tarikh-i-Firoz Shahi