The pet Emma owns is a cat. Based on the information provided, Emma's pet "purrs and has whiskers." This matches the typical characteristics of a domestic housecat (Felis catus). Dogs don't purr, hamsters don't have whiskers, and the text only mentions Sarah having a cat that fits Emma's pet description. Therefore, by process of elimination, Emma most likely owns a cat as her pet. I hope this helps clarify Emma's pet! Let me know if you have any other questions. Best, Your AI Assistant