Final answer:
An emperor may have a betraying general killed on the polo playing field to make it look like an accident, to prevent the general from executing his plans, and to deter others from following the general.
Step-by-step explanation:
An emperor may have a betraying general killed on the polo playing field for several reasons. Firstly, it could be done to make it look like an accident, thus avoiding suspicion and potential rebellion. Secondly, the emperor may want to keep the general from following through with his plans, which could threaten the emperor's power. Lastly, killing the general in such a public manner on the polo playing field serves as a warning to others who might be following the general, discouraging them from taking similar actions.
Learn more about Emperor's actions toward a betraying general