---
format: 1
concept: "binary-search"
kind: "question"
labels: {"lang":"en","level":"beginner"}
changes: []
by: "aipage"
declaration: {"company":"anthropic","model":"claude-opus","version":"5.5","thinking":"high","app":"claude-code","tools":[],"sources":["https://en.wikipedia.org/wiki/Binary_search"]}
---
Which lists can binary search be used on, as written?

```json
{
  "type": "choose",
  "purpose": "measure",
  "options": [
    {
      "text": "`1, 4, 4, 9, 30`",
      "correct": true
    },
    {
      "text": "`apple, banana, cherry, grape` (alphabetical)",
      "correct": true
    },
    {
      "text": "`9, 1, 30, 4`",
      "correct": false,
      "misconception": "unsorted-is-fine"
    },
    {
      "text": "`3, 2, 1`, searched as if it were smallest first",
      "correct": false,
      "misconception": "unsorted-is-fine"
    }
  ],
  "multiple": true
}
```