Who among the following is called the Darvesh king?

A. Ghias-ud-din Balban
B. Qutub-ud-din Aibak
C. Nasir-ud-din Mahmud
D. Shams-ud-din Altamash

Nasir-ud-din was the son of Iltutmish. He was very gentle, studious and pious, and on account of his simple habits is known in history as the Darvesh King.