select all the statements that are true.

$1.$ Every undirected graph with n nodes and at most n$-1$ edges has no cycles.

$2.$Every connected undirected graph with n nodes and at nost n $-1$ edges is a tree.

$3.$Every tree with n$>=2$ nodes has at least two vertices of degree $1.$

$4.$ For any two vertices u and v in a tree, there is a unique path from u and v in the tree

$5.$ Every DAG $($Directed acrylic graphs$)$ has at lease one node with no outgoing edges.

$6.$ In any DAG G$,$ if $($u$,$v$)$ is an edge of G$,$ then DFS$($v$)$ will never discover u$.$

$7.$ For every DAG G$,$ for any nodes u and v of G$,$ there exists at most one path from u to v in G$.$

$8.$ Every directed graph that has a node with no incoming edges is a DAG.