Question

what should you do around horseback riders and slow - moving vehicles?
speed up so as to get by the horseback rider or slow moving vehicle quickly.
slow down, be prepared to stop, and if you pass, do it cautiously.
continue driving as normal.

Explanation:

This is the safe, standard driving practice around horseback riders (who may have skittish animals) and slow-moving vehicles, as it minimizes risk of startling the horse or causing a collision. Speeding up or driving normally creates unnecessary danger.

Answer:

Slow down, be prepared to stop, and if you pass, do it cautiously.