Final Answer:
One unit of Furlong in distance used in horse racing is exactly 660 feet. Therefore, the correct option is a) Furlong.
Step-by-step explanation:
A furlong is a unit of distance historically used in the imperial system of measurements, especially in horse racing. It is equivalent to 660 feet or 201.168 meters. This measurement is particularly significant in horse racing tracks, where the length of the track or race is often expressed in furlongs. The term "furlong" originates from Old English, meaning "furrow long," referring to the length of a furrow in one acre of a plowed field. In modern usage, while many imperial units have been phased out, the furlong remains common in horse racing contexts.
The other options provided do not match the defined measurement of 660 feet used in horse racing. A hectare is a unit of area, equal to 10,000 square meters and not a measurement of distance. A nautical mile is approximately 6,076 feet, which differs from the specified 660 feet in the question.
A cubit is an ancient unit of length typically based on the length of a forearm, and its measurement varies widely across different historical contexts, making it incompatible with the defined distance in the question. Therefore, the correct answer that corresponds to the specified distance of 660 feet used in horse racing is the furlong. Therefore, the correct option is a) Furlong.