Matrices

Which one of the following matrices can be obtained by performing elementary row transformations on the 3 3 identity matrix ?

1. bmatrix 1 & 1 & 1 \ 1 & 1 & 1 \ 1 & 1 & 1 bmatrix
2. bmatrix 1 & 1 & 1 \ 2 & 3 & 4 \ 1 & 2 & 1 bmatrix
3. bmatrix 1 & 1 & 1 \ 2 & 3 & 4 \ 2 & 5 & 8 bmatrix
4. bmatrix 1 & 1 & 1 \ -1 & 1 & 2 \ 0 & 2 & 3 bmatrix

Consider the matrix P = pmatrix 2 & 0 & 0 \ 0 & 2 & 0 \ 0 & 0 & 3 pmatrix. Let the transpose of a matrix X be denoted by XT. Then the number of 3 3 invertible matrices Q with integer entries, such that Q-1 = QT and PQ = QP, is

1. 32
2. 8
3. 16
4. 24