Question $3(2$ points$)$

Consider an undirected graph $G$ with six vertices labeled from $\text{'}a\text{'}$ to $\text{'}f\text{'}.$ Its adjacency matrix representation is as follows:

$\{\begin{array}{c}\text{:}[]\\ a\\ b\\ c\\ d\\ e\\ f\end{array},([a,b,c,d,e,f],[0,3,0,2,4,0],[3,0,4,0,2,0],[0,4,0,0,4,2],[2,0,0,0,3,0],[4,2,4,3,0,4],[0,0,2,0,4,0])$

Which of the following edges cannot be in any minimum spanning tree of G$?$

$(b,c)$

$,$ e$)$

$(a,e)$

$($e$,$ f$)$