Answer:
I think its a
Step-by-step explanation:
Because it gives a more specific evidence which is always reassuring. With d its obvious its a broader answer as it isn't very accurate because pretty sure there are sane people at night. With b and c its more in general and if you were to actually drive at night you would most likely to slow down your speed during nighttime knowing the consequences if you were to drive at a speed faster than what you are more comfortable with.