Final answer:
When another vehicle is merging on the freeway, the best practice is to change lanes safely or to adjust your speed without stopping completely. Always maintain awareness of merging traffic and facilitate their entrance to the highway to promote safety.
Step-by-step explanation:
When you're driving on an Interstate (freeway) and another car is attempting to merge into your lane, the safest course of action is to maintain your speed if possible and move over to the next lane if it's safe to do so. This allows the merging vehicle the space to enter the roadway. As a driver, it's important to be aware of traffic attempting to merge and to facilitate this when you can to help maintain the flow of traffic and to ensure the safety of all road users.
If you are unable to change lanes, reduce your speed to allow the merging vehicle some space, or if the situation requires it, slightly increase your speed to avoid a collision. However, you should never come to a complete stop on the freeway unless the traffic conditions require it, as this can cause a serious hazard. Additionally, running alongside or towards another vehicle, such as an ambulance, is never advisable.
The mention of a rabbit attempting to cross three lanes of a freeway in the question is not directly relevant to the rules of the road concerning vehicles and should be disregarded when determining the appropriate response to a merging vehicle.