For the following stress matrix, the first invariant of the stress tensor is the trace of a matrix, the sum of diagonal element: I1 = 11 + 22 + 33. The second invariant of matrix is equal to _________ ( begin{vmatrix} sigma_{11} & sigma_{12} & sigma_{13} sigma_{21}& sigma_{22} & sigma_{23} sigma_{31}& sigma_{32} & sigma_{33} end{vmatrix} )

• A. Sum of all the elements of the matrix
• B. Sum of first column elements
• C. Sum of first raw elements
• D. Sum of all the principal minors of the matrix