题目内容：
根据以下材料，回答题Biorobotics
Surgeons are being able to enter the eye to carry out operations--atleast in a virtual sense.
Techniques derived from virtual reality- the computer system that immerses operations in an artificial computer-generatedworld -- will allow surgeons to feel as if he could see the inside of, the eyeduring an operation, creating the illusion that they are actually there.
Researchers at the Biorobotics (生物机械人技术) Laboratory of McGill University in Montreal are building a robot, known as Micro SurgeryRobot-1 (MSR-I for short) , that will perform delicate operations under thecontrol of a human surgeon. The robot is specifically designed for performing eye surgery but could have other applications, such as the removal ofbrain tumors.
The system could also be used to allow surgeons and theirstudents to practice simulated surgery that feel like the real thing -- withoutthe real consequences for the patients.
During the operations, the surgeon manipulates a set of controls knownas the master. These are connected through a high-performance computer tothe robot. Both the master and the robot have two limbs. When the surgeonmoves the master's limbs, the robot's limbs move in exactly the same way, except that the movements can be sealed down as much as a thousandtimes. This will eliminate hand tremor and poor accuracy and thus reducethe damage to the eye that can occur with present microsurgery techniques.Each of the robot's limbs has a minimum movement of one micrometer--more than one hundred times the precision of the human hand.
The computer also creates a three-dimensional robot's eye view of theinside of the eye that the surgeon can see by wearing a virtual reality helmet (头盔) that has a small lens in front of each eye.
To provide the surgeon with such a realistic experience, MSR-I must beable to move rapidly,but this requires extremely fast computing. To handlethe computational demands of instant interaction, the McGill team is constructing its own parallel-processing computer. It is also studying areas such asmuscle mechanism, artificial intelligence and optics, and has already built another microrobot, MR-I, capable of manipulating a single living cell.
The so-called "virtual reality" mentioned in this passage refers to __________. A．operations conducted inside the eye
B．computer-created illusions that assist in operations
C．new applications of visual technology
D．new notions that help improve microsurgery
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