premise: Polo (Persian: چوگان "chogān") is a team sport played on horseback. The objective is to score goals against an opposing team. Players score by driving a small white plastic or wooden ball into the opposing team's goal using a long-handled mallet. The traditional sport of polo is played on a grass field up to 300 by . Each polo team consists of four riders and their mounts.
hypothesis: Only Arabian horses are used to play polo.
reason: It is not stated what kind of horses are used in polo, so the statement could be either correct or incorrect. The system probably thought it was improbable.