What must you do when merging onto a freeway?

When merging onto a freeway, it is crucial to yield to vehicles that are already on the freeway. This means that as you approach the merge point, you should assess the speed and position of the vehicles in the lane you are merging into. Yielding ensures a smooth transition from the entrance ramp into the main flow of traffic, which is typically moving at higher speeds. By doing so, you allow for safe merging and help to maintain the flow of traffic, reducing the risk of accidents caused by sudden stops or forced entries.

The other choices involve actions that could create safety hazards. Forcing your way into traffic can lead to collisions, while stopping before merging is generally unsafe as it disrupts the flow of traffic. Slowing down significantly to find a gap can also pose risks, as it may confuse other drivers and lead to dangerous situations on a busy freeway. Hence, the appropriate action is to yield to existing traffic for a safer merging process.