The correct answer is: D. Creates images on the screen by scanning straight-line vectors between selected points.
A refresh-vector CRT is a type of cathode ray tube (CRT) that uses a technique called vector scanning to create images on the screen. In vector scanning, the electron beam is not constantly moving across the screen, but instead is used to draw lines between selected points. This allows for the creation of smooth, curved lines and shapes, which are not possible with raster scanning, the other main type of CRT scanning.
Option A is incorrect because the beam does not constantly travel across the screen. Instead, it is used to draw lines between selected points.
Option B is incorrect because the anode voltage is not used to make changes on the image. Instead, the anode voltage is used to accelerate the electron beam.
Option C is incorrect because the electron gun does not continuously flood the surface of the tube. Instead, it is used to emit a stream of electrons that are focused into a beam.
Option E is incorrect because the refresh-vector CRT does use the technique described in option D.