READ_ONLY_ACCESS
[
  {
    "id": "ct-w09-000",
    "front": "Week 9 Diagnostic: Which data structure does Breadth-First Search (BFS) use to manage the discovery frontier?",
    "back": "Answer: B — BFS processes nodes in level order using a First-In, First-Out Queue."
  },
  {
    "id": "ct-w09-001",
    "front": "Week 9 Diagnostic: Why is a `visited` set or boolean array necessary during graph traversal?",
    "back": "Answer: B — In graphs with cycles, failing to track visited vertices causes the traversal algorithm to loop infinitely."
  }
]