What is the safest practice when overtaking a vehicle on a two-lane highway?

The safest practice when overtaking a vehicle on a two-lane highway is to ensure you can see the vehicle being passed in your rearview mirror. This indicates that you have successfully completed the maneuver and that it is safe to return to your lane. By confirming that the overtaken vehicle is no longer in your blind spot, you reduce the risk of a collision. This practice promotes awareness of your surroundings and ensures that the lane is clear behind you, which is crucial for safely merging back after passing.

Considering the other choices, using your horn to alert the vehicle being passed may create confusion or anxiety, and it can be unnecessary and potentially distracting. Cutting back into your lane too soon can pose risks if the vehicle you have overtaken is not sufficiently behind you, increasing the chance of side-swiping. Signaling before overtaking is important, but it alone does not ensure that the maneuver is safe; visibility of the vehicle being passed in your rearview mirror is a more critical factor for safe lane changes.