ans is D (it is illusion of very large main memory limited only by secondary memory size)
Virtual means absence in existence , presence in effect
Virtual reality (or VR) is a computer technology that uses software-generated realistic images, sounds and other sensations to replicate an a real environment or an imaginary setting, and simulates a user's physical presence in this environment to enable the user to interact with this space. A person using virtual reality equipment is typically able to "look around" the artificial world, move about in it and interact with features or items that are depicted. Virtual realities artificially create sensory experiences, which can include sight, touch, hearing, and, less commonly, smell.
