What practice enhances safety when merging into traffic?

Adjusting your speed to match incoming traffic is crucial for safety when merging. This practice ensures that you can seamlessly integrate into traffic without disrupting the flow of vehicles. By aligning your speed with that of the vehicles already on the road, you reduce the risk of collisions, as it enables you to find an appropriate gap to enter safely.

Maintaining a consistent speed alone may not be sufficient if that speed is not suited to the flow of traffic, which can create dangerous situations. Arm signaling to other motorists is helpful to indicate your intentions but does not directly influence your ability to merge safely. Relying solely on mirrors can be dangerous, as it may prevent you from detecting vehicles in blind spots. Thus, while the other options have merits in their own contexts, adjusting your speed to match that of incoming traffic is fundamentally key to ensuring a safe merge.