The Breadth First Search (BFS) algorithm has been implemented using the queue…

Key insight: BFS visits nodes level by level using a queue and marks nodes when they are enqueued, so nodes discovered earlier are always visited earlier.

• Step 1: Start at P. Queue = [P]. Visit P and enqueue its neighbors in some order; assume O then Q. Visited so far: P.

• Step 2: Dequeue O and visit it. O enqueues its unvisited neighbor N (Q was already enqueued). Visited order: P, O.

• Step 3: Dequeue Q and visit it. Q enqueues its remaining unvisited neighbor M (N already enqueued). Visited order: P, O, Q.

• Step 4: Dequeue N and visit it. No new nodes are added. Visited order: P, O, Q, N.

• Step 5: Dequeue M and visit it; it enqueues R. Visited order: P, O, Q, N, M.

• Step 6: Dequeue R and visit it. Final BFS order: P O Q N M R.

Conclusion: POQNMR is achievable with BFS (starting at P and with the adjacency ordering shown), so the sequence POQNMR is a valid BFS visitation order. The other sequences are not possible under standard BFS behavior because they require visiting nodes discovered later before earlier-enqueued nodes.