The correct answer is: C. the number of addressable elements on the tube.
A CRT (cathode ray tube) is a vacuum tube that uses an electron beam to display images on a screen. The resolution of a CRT is determined by the number of addressable elements on the tube, which are the tiny dots that make up the image. The more addressable elements there are, the higher the resolution of the image.
Option A is incorrect because the speed at which a monitor can accept data from the computer is not related to the resolution of the image.
Option B is incorrect because the number of phosphor dots that react when hit by the electron beam is not the same as the number of addressable elements on the tube.
Option D is incorrect because the number of pixels in each square centimeter is not a measure of resolution.
Option E is incorrect because the number of addressable elements on the tube is the correct answer to the question.