Car Drawing Toy

How does the inductive sensor in the car (a toy for children) work?
Those things that children have to draw a line or the shape and the car moves on. What exactly is happening between the car and the child's path drew? All help is appreciated.
This would be a light or optical sensor, not inductive sensor (unless the line is made with a marker that has magnetic ink or electrically conductive. Induction can be electric or magnetic. If the car is a steel wire (a coat hanger ex) that is hidden under a pece of white paper, then it is inductive and optical.
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