The book on which of the following subjects is kept on the top?
Data inadequate
C's book is at the top, and we are told that the book on subject R is immediately above the book on subject T. Based on the positioning of books and persons, it follows that the book on subject R must be kept at the top. This is the only arrangement that satisfies the conditions for the books.
Thus, the correct answer is (b) R.
We know C's book sits at the top of the stack, and separately that the book on subject R sits immediately above the book on subject T.
With T ruled out as being between P and Q, and U ruled out as being at the bottom, R — sitting immediately above T and matching C's fixed top position — must be the subject on top.
Hence, the correct answer is R.
