Answer:
internal stimulus of hunger
Step-by-step explanation:
Lions do not fear externally or internally of the zebra because they eat the zebra once they kill it and they are chasing after it so no fear what so ever.
Lions are naturally lazy and hunger is normally why they would be hunting because they need food to survive, however this is not always the case.
there have been a pair of documented pair of male lions known as the Tsavo Man-Eaters, who hunted for sport. Their den contained animal and man bones.
they actually made a movie about it, If you want to watch the movie just look up Ghost in the Darkness. You can actually see the lions in the Field Museum of Natural History in Chicago, Illinois.
Hope this helped you!