What are the foot rests used when riding horses called?

The correct answer is "stirrups" because stirrups are specifically designed as footrests for riders when mounted on a horse. They are attached to the saddle and provide a secure place for the rider's feet, allowing for better balance and control while riding. This is essential for maintaining stability during riding and for mounting and dismounting safely.

Bridles are used to direct and control the horse and do not serve any function related to foot support. Saddles provide a seat for the rider and may include the stirrups but do not themselves act as footrests. Reins are the straps used by the rider to guide and manage the horse's direction and speed, and they are disconnected from any foot support. Each of these items plays a distinct role in equestrian equipment, but stirrups are uniquely designated for foot placement.