$1314-860158$ Test Question $19$ of $20$ This test: $20$ point$($s$)$ pos This question: $1$ point$($s a$.$ Give the order of the given matrix. b$.$ If $A=[a_{ij}],$ identify $a_{31}$ and $a_{13},$ if possible. $\left[\begin{array}{ccc}5& -6& 6\\ -7& 4& -8\end{array}\right]$ a$.$ The order of the given matrix, in the form $mn,$ is $.$ b$.$ Identify $a_{31}.$ Select the correct choice below and, if necessary, fill in the answer box to complete your choice. A$.a_{31}=$ B$.$ Element $a_{31}$