The Turkan-i-Chihalgani was a group of forty Turkic slaves of Iltutmish, who held remarkably high positions in the Delhi Sultanate. Option 1, Iltutmish, was the one who created this group, hence, he couldn`t be the one to destroy it. Option 3, Alauddin Khalji and option 4, Muhammad bin Tughluq ruled after the era of Turkan-i-Chihalgani, hence they could not have been responsible for their downfall. The correct answer, therefore, is option 2, Balban, who ascended the throne after Iltutmish. Balban, originally a member of Turkan-i-Chihalgani, viewed it as a threat to his rule and systematically eliminated and subdued its influence, thereby breaking and destroying its power.