What should you always do before changing lanes or merging into traffic?

Answer: B — Signal your intentions to other drivers

Before changing lanes or merging into traffic, signaling your intentions to other drivers is crucial for safe driving. This action communicates your next move to other road users, allowing them to respond appropriately. Signaling helps prevent misunderstandings and reduces the likelihood of accidents by ensuring that fellow drivers are aware of your intention to change lanes or merge. Using your turn signal gives other drivers the opportunity to adjust their speed or position, creating a safer environment for everyone on the road. This practice is fundamental to the rules of the road and is part of defensive driving strategies, which prioritize awareness and communication among drivers. Other options, such as checking only the rearview mirror, honking, or significantly reducing speed, do not effectively convey your plans to those around you and can lead to confusion or hazardous situations.