Answer:
difficult for both the horse and rider
Step-by-step explanation:
The excerpt makes it clear that the Pony Express operation is important to remember, because it is a record not only of the American organizers' courage and genealogy, but it must also be remembered because it is a representation of the socrificio of man and animals for progress. The operation of Pony Express was a difficult achievement that required a lot of effort from the man and his horse. For this reason we can say that the excerpt gives clear information that the operation of Pony Express was difficult for the horse and rider.