Let $\{$G$=($V$,$E$),$ s$,$ t in V$,$ c$($e$)$ for e in E$\}$ be a network. For a given valid flow f$,$ you are told that the edge e from node u to node v satisfies f$($e$)=$ c$($e$)($that is$,$ the edge e is saturated$).$ Which of the following are always true?

$1.$ The reversed edge from node v to node u is in the residual network of G$^$f$.$

$2.$ The size of the flow f is at least c$($e$)$

$3.$ All paths from the source s to the sink t must traverse the edge e$.$

$4.$ There exists a path from s to t with capacity equal to c$($e$).$