Before changing lanes you should:

Answer: D — All of the above

Before changing lanes, it's important to check your surroundings to ensure safety. Looking in your rearview mirror is important as it allows you to see if any vehicles are approaching from behind. This can give you an idea of the speed and distance of other vehicles on the road. Using your turn signals is also crucial as it communicates your intention to other drivers, giving them enough time to react and adjust their speed. Furthermore, checking your blind spot is important because it covers the area that your rearview and side mirrors might miss. It's always important to perform all of these actions before changing lanes to ensure the safety of yourself and other drivers on the road. Therefore, the correct answer is D.