The incidence matrix of a graph is given below:​​\(A = \left[ {\begin{array}{*{20}{c}} { - 1}&0&1&1&{ - 1}&0\\ 1&{ - 1}&0&0&0&{ - 1}\\ 0&1&{ - 1}&{ - 1}&1&1\end{array}} \right]\)Number of possible trees are

• A. 12
• B. 11
• C. 8
• D. 14