Select the most appropriate one-word substitution for the given group of words.

One who rides horses in races

jockey

The most appropriate one-word substitution for "one who rides horses in races" is jockey.

The other words in the options, porter, sprinter, and athlete, do not mean the same thing.

• Porter is a person who carries luggage or other heavy objects.
• Sprinter is a runner who specializes in short-distance races.
• Athlete is a person who is physically active and participates in sports or other physical activities.

A jockey is a professional horse rider who competes in horse races. They are typically very small and light, as this gives them an advantage in races. Jockeys must be skilled riders and have a good understanding of horse racing.