Answer: D
A data set's mode has the following properties:
- Unimodal: Has one mode (e.g., {1, 2, 2, 3}).
- Bimodal/Multimodal: Has two or more modes (e.g., {1, 1, 2, 3, 3}).
- No mode: If all values appear with the same frequency (e.g., {1, 2, 3, 4}).
Therefore, all of the above statements are possible.