<human>: How do you do this: How to make sure picture frame is level.

OPTIONS:
- Place level on top of picture frame. Make sure bubbles are completely straight across the horizontal line on the level.
- Place ruler on top of picture frame. Make sure bubbles are completely straight across the horizontal line on the ruler.
<bot>: Place level on top of picture frame. Make sure bubbles are completely straight across the horizontal line on the level.