Which statement best describes DFS use?

• A. Exploring as deep as possible to discover paths and topological ordering.
• B. Visiting each node exactly once.
• C. Always yields the shortest path.
• D. Requires a queue data structure.

Answer: (A)

Depth-first search is about plunging down one branch as far as possible before backtracking to explore other branches. This deep exploration makes it well-suited for revealing long paths and for producing an ordering of nodes based on finishing times, which is how you can derive a topological order in a DAG. It does not guarantee the shortest path between two nodes—that's a property of breadth-first search, which expands outward in layers. DFS uses a stack or recursion, not a queue, which is another key difference from BFS. So the best description of DFS use is this deep, backtracking exploration pattern that helps uncover paths and ordering, rather than shortest routes or the need for a queue.