Post Order Properties: Forward Edge
a) A forward edge is an edge that goes from a node to one of its ancestors in a rooted tree.
b) A forward edge is an edge that goes from a node to one of its descendants in a rooted tree.
c) A forward edge is an edge that goes from a node to a different connected component in a graph.
d) A forward edge is an edge that goes from a node to a sibling in a tree.
