Which activity is included in the regular business of selling equine?

Transporting more than 20 equines a year is indeed an activity that falls under the regular business of selling equine. This indicates that the individual is engaged in a commercial activity that involves the movement of horses, which is a significant component of equine sales and distribution.

In this context, the other options do not reflect activities that directly pertain to the commercial sale or business aspect of equines. Owning a single horse for personal use does not imply any business activity, as it is more about personal ownership rather than commercial transactions. Providing horseback riding lessons on weekends is typically classified as an instructional service rather than a business focused on the buying and selling of horses. Similarly, holding riding competitions may involve equines, but it is more closely aligned with event organization rather than the straightforward economic activity of selling horses. Therefore, the transportation of a large number of equines clearly demonstrates an active role in the business of equine sales.