Which requirement is essential for a virtual reality experience?

Sensory feedback is an essential requirement for a virtual reality experience as it enhances immersion and engagement. In virtual reality (VR), sensory feedback allows users to receive information through their senses, such as sight, sound, and touch, which creates a more realistic and interactive experience. This feedback can come from various sources, like haptic devices that simulate touch or auditory cues that correspond to actions within the virtual environment. By providing sensory input, VR can effectively simulate real-world interactions and help users feel more "present" in the virtual space.

The other options, while they may enhance a VR experience, are not fundamental requirements. A scoring system is primarily relevant in gamified environments and may not be necessary for all VR scenarios. Personal avatars can add a sense of identity and customization, but they don't define the core experience of virtual reality itself. Augmented reality is a different concept, overlaying digital elements onto the real world, rather than immersing users in a fully virtual environment, which is specific to virtual reality.