Answer the following question: Information:  - A spur is a metal tool designed to be worn in pairs on the heels of riding boots for the purpose of directing a horse to move forward or laterally while riding . It is usually used to refine the riding aids ( commands ) and to back up the natural aids ( the leg , seat , hands and voice ) . The spur is used in many equestrian disciplines . There are rules in most equestrian organizations about spur design , use and penalties for using spurs in any manner that constitutes animal abuse .  - Poker is a family of gambling card games, but is often considered a skill based game. All poker variants involve betting as an intrinsic part of play, and determine the winner of each hand according to the combinations of players' cards, at least some of which remain hidden until the end of the hand. Poker games vary in the number of cards dealt, the number of shared or "community" cards, the number of cards that remain hidden, and the betting procedures.  - Riding aids are the cues a rider gives to a horse to communicate what they want the animal to do. Riding aids are broken into the "natural aids" and the "artificial aids".  - A boot is a type of footwear and a specific type of shoe. Most boots mainly cover the foot and the ankle, while some also cover some part of the lower calf. Some boots extend up the leg, sometimes as far as the knee or even the hip. Most boots have a heel that is clearly distinguishable from the rest of the sole, even if the two are made of one piece. Traditionally made of leather or rubber, modern boots are made from a variety of materials. Boots are worn both for their functionality  protecting the foot and leg from water, extreme cold, mud or hazards (e.g., work boots may protect wearers from chemicals or use a steel toe) or providing additional ankle support for strenuous activities with added traction requirements (e.g., hiking)  and for reasons of style and fashion.  - A riding boot is a boot made to be used for horse riding. The classic boot comes high enough up the leg to prevent the leathers of the saddle from pinching the leg of the rider, has a sturdy toe to protect the rider's foot when on the ground and has a distinct heel to prevent the foot from sliding through the stirrup. The sole is smooth or lightly textured to avoid being caught on the tread of the stirrup in the event of a fall.  - H.O.R.S.E. is a form of poker commonly played at the high-stakes tables of casinos. It consists of rounds of play cycling among:    After reading the paragraphs above, we are interested in knowing the entity with which 'spur' exhibits the relationship of 'subclass of'. Find the answer from the choices below.  Choices: - animal  - community  - cycling  - footwear  - gambling  - horse  - part  - poker  - skill  - winner
Answer:
footwear