What should you do before entering a lane of traffic?

Answer: D — Signal then merge

Before entering a lane of traffic, it is important to signal then merge. This alerts other drivers of your intention to change lanes and gives them time to adjust their speed if necessary. Checking your rearview mirror and looking over your shoulder are also important precautions to take before changing lanes, but they are typically done after signaling and before actually merging. Tapping your brakes is not necessary and could actually confuse other drivers, so it should be avoided. Ultimately, signaling and checking mirrors and blind spots are all important steps to ensure safe lane changes.