Let A be m × n matrix and b an n × m matrix. It is given that determinant ( Im + AB ) = determinant ( In + BA ), where Ik is the k × k matrix. Using the above property, the determinant of the matrix given below is
[ 2. 1. 1. 1. ]
[. 1. 2. 1. 1. ]
[. 1. 1. 2. 1. ]
[. 1. 1. 1. 2. ]

a. 2
b. 5
c. 8
d. 16