How should you pass horse riders on the road?

Answer: B — Slow and wide

When passing horse riders on the road, it is important to give them enough space to feel comfortable and safe. This includes passing slowly and keeping a wide distance in order to avoid startling the horse or causing any accidents. Options A and C are incorrect because passing quickly or at the speed limit can startle the horse and put both the rider and the passing driver in danger. Option D is also incorrect as honking can startle the horse and should only be used in emergency situations. Therefore, option B - passing slowly and wide - is the safest and most courteous way to pass horse riders on the road.