The correct option is B Halaku
Halaku followed a diplomatic and military approach towards the Mongols. When he was a naib under Nasiruddin Mohammad Shah, he sent an embassy to Halaku who, apart from the Oghtai-Chaghtai branch of Mongols ruling in Transoxiana, was one of the important successors of Changez khan and was Khan of Persia. Balban used military approach later on when he himself became Sultan. By then, Halaku had also died.