When following a vehicle closely, you should

Answer: B — Keep within one car length

Following a vehicle closely can be dangerous for various reasons. Option A is incorrect because driving in the center lane does not necessarily guarantee a safe distance from the vehicle in front of you. Option C is also not the recommended course of action as changing lanes often without proper signaling can increase the risk of accidents. Option D is also incorrect as flashing headlights may cause distractions for the driver in front of you. Keeping within one car length is important as it allows you to have a clear view of the road ahead and enough time to react in case of sudden stops or changes in traffic. This is why option B is the best choice when following a vehicle closely.