Consider the following statements about cathode rays.

I. These moves from cathode to anode.

II. These are visible rays.

III. Television picture tubes are cathode rays tubes.

IV. In the absence of electrical or magnetic field these rays travel in a straight line.

Choose the correct statement from the above and mark the correct option.

Cathode rays move from cathode to anode. These rays themselves are not visible but their behavior can be observed with the help of certain kind of materials (fluorescent or phosphorescent) which glow when hit by them. Television picture tubes are cathode ray tubes and television pictures result due to fluorescence on the television screen coated with certain fluorescent or phosphorescent materials.