UPSC NDA Math Model Paper 1

Here, determinant of matrix = 16 and order = n = 3
Determinant formed by replacing each of its elements by its cofactor = determinant of transpose of adjoint
= determinant of adjoint of matrix .....(∵ The determinant of a square matrix is the same as the determinant of its transpose.)
=( determinant of matrix )n−1
=(16)3−1
=(16)2
=256
Hence, option (3) is correct.