Consider performing depth-first search (DFS) on an undirected and unweighted…

Consider performing depth-first search (DFS) on an undirected and unweighted graph G starting at vertex 𝑠. For any vertex 𝑢 in G, 𝑑[𝑢] is the length of the shortest path from 𝑠 to 𝑢. Let (𝑢, 𝑣) be an edge in G such that 𝑑[𝑢] < 𝑑[𝑣]. If the edge (𝑢, 𝑣) is explored first in the direction from 𝑢 to 𝑣 during the above DFS, then (𝑢, 𝑣) becomes a ______ edge.