$2.(10$ Points$)$ For each of the following networks, how would you define the nodes and edges in order to model the network? Would the network be weighted or non$-$weighted? Directed or non$-$directed?

$($a$)$ An ant colony

$($b$)$ A city road and highway network

$($c$)$ A VLSI circuit $($d$)$ A gas pipeline

$($e$)$ Evolution of species