Final answer:
The most likely scenario described is that the hyena is attacking the zebra, as hyenas are predators known to hunt and consume zebras in the wild.
Step-by-step explanation:
Given the behaviors described between zebras and other animals on the African savanna, when assessing the situation between a zebra and a hyena, the most accurate description would be that the hyena is attacking the zebra. This is based on understanding animal behavior within predator-prey dynamics, where hyenas, as predators, often hunt and consume prey such as zebras. Unlike the cooperative and symbiotic relationships zebras have with wildebeest and ostriches, interactions with hyenas commonly involve predation.
In the wild, zebras and hyenas do not play together as cooperative species might; rather, hyenas are a real and dangerous threat to zebras. Hyenas are known to attack and consume zebras, often targeting the young, sick, or isolated individuals within a herd. Despite the potential for violence in this interaction, we cannot conclude without additional context whether the hyena in this scenario has already bitten the zebra's leg off, but we can infer that an attack is more likely than peaceful coexistence or play behavior.