Awards Committees Need to Be Formed to Review Potential Award

Awards committees need to be formed to review potential award recipients. In the past, three people have been assigned to review each applicant. The only stipulation is that a reviewer cannot be assigned to an applicant if the applicant is a co-worker. The matrix below shows 9 reviewers, 3 candidates, and a matrix. If an entry in the matrix contains an "X", then that specific reviewer is ineligible to review an applicant's material. For example, reviewer 1 cannot review materials submitted by candidate B. It is possible that some reviewers may not receive an assignment.
Applicant
$$\begin{array} { | c | c | c | c | } \hline \text { Reviewer } & \text { A } & \text { B } & \text { C } \\\hline 1 & & \mathrm { X } & \\\hline 2 & \mathrm { X } & & \\\hline 3 & & & \mathrm { X } \\\hline 4 & & & \\\hline 5 & \mathrm { X } & & \\\hline 6 & & \mathrm { X } & \\\hline 7 & & \mathrm { X } & \\\hline 8 & & & \mathrm { X } \\\hline 9 & & \mathrm { X } & \\\hline\end{array}$$
-Formulate this as an assignment problem in which two reviewers are assigned to review each applicant's material.