For the following stress matrix, the first invariant of the stress tensor is the trace of a matrix, the sum of diagonal element: I1 = σ11 + σ22 + σ33. 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