The options provided were Abul Fazal, Shah Wallulah Dehlvi, Dara Shikoh and Ahmad al-Sirhindi.
Karan tweeted on Tuesday night that he knew the Rs 1 crore answer.
"I knew the 1 crore answer! 'Dara Shikoh and so would you have Ranveer. 'Takht'," he wrote.
Actor Ranveer Singh will be seen playing the role of Dara Shikoh in Karan's upcoming film "Takht", which also stars Vicky Kaushal, Kareena Kapoor, Alia Bhatt, Bhumi Pednekar, Anil Kapoor and Janhvi Kapoor.