If the horses take the same number of steps, the horse with the longer stride will go farther. So, in a race, the horse with the longest legs will win the race. If you compare two horses, the horse with longer legs will also have stronger legs, and will be faster. The stronger and faster horse will be able to run a given distance more quickly. Therefore, the horse with the longest legs in a given race will win that race.
Horses have long legs, compared to donkeys.
Racing donkeys are slower than racing horses. Thus, the winning horse in a horserace will be the horse with the longest legs. This argument fails the R condition because the comparative speeds of donkeys and horses tells us nothing about the speed of various horses. Among the horses in this race, the horse with the longest legs has won every race in which it has been entered. The horse with the longest legs is in very good condition, and is being ridden by the best jockey.