Leaning in your seat while glancing in the mirrors:

Leaning in your seat while glancing in the mirrors can indeed improve the sight angle in your mirrors. This adjustment can help you see blind spots more effectively, as it alters your perspective and can enhance your field of view. Adjusting your body position can make it easier to spot other vehicles or obstacles that may not be clearly visible from a standard seated position.

In contrast, the other options suggest practices that do not align with safe driving techniques. Signaling before changing lanes is an essential practice for alerting other drivers of your intentions and maintaining safety on the road. Leaning in might not inherently serve as a distraction, but moving your attention away from the road ahead without careful consideration can potentially compromise your focus. Therefore, while improving the sight angle is beneficial, the other suggested behaviors either misrepresent the importance of signaling or imply an unsafe practice of distraction.