Final answer:
The experience of the elephants and the African veldt unsettles Jonas because the virtual experiences have become almost indistinguishable from reality, causing concern over the psychological impact on his children.
Step-by-step explanation:
The unsettling experience of the elephants for Jonas stems from the blending of virtual and real experiences that become disturbingly indistinguishable. In the context of the passages provided, which seem likely from Ray Bradbury's 'The Veldt', the children's nursery transforms into a realistic African veldt with lions and elephants that provide an immersive, yet terrifying experience.
George Hadley, realizing how intensely real the simulations have become and the impact on his children, feels apprehensive about the psychological effects of such a high degree of realism. The lines detailing the African veldt with lions imply a technological environment that is capable of generating lifelike experiences, complete with sensory feedback like sights, sounds, and smells, making the virtual dangers feel all too real.