Ibadat Khana at Fatehpur Sikri was

(a) the mosque for the use of Royal Family
(b) Akbar's private prayer chamber
(c) the hall in which Akbar held discussions with scholars of various religions ✓ UPSC's answer
(d) the room in which the nobles belonging to different religions gathered to discuss religious affairs

Why the answer is (c)

• The Ibadat Khana (House of Worship), built by Akbar at Fatehpur Sikri in 1575, was the hall where he held religious debates — first among Muslim theologians, then from 1578 with Hindus, Jains, Parsis and Jesuits — option (c).

• These discussions led to the Mahzar (1579) and Din-i-Ilahi (1582).

• It was not a mosque (a), a private prayer room (b) or a nobles' meeting room (d).

• Hence option (c).

Why the other options are wrong

(a) the mosque for the use of Royal Family: It was a debating hall, not a mosque.
(b) Akbar's private prayer chamber: It was not a private prayer chamber.
(d) the room in which the nobles belonging to different religions gathered to discuss…: Scholars, not nobles, debated there.

Asked in the GS Paper I of the UPSC Civil Services Preliminary Examination 2014, held on 24 August 2014. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.