Concept:Cathode rays are streams of fast-moving electrons emitted from the cathode in a discharge tube.
Explanation:Cathode rays travel along straight lines.
They are negatively charged particles, so they get deflected by both electric and magnetic fields.
Hence, option D is false.
When cathode rays strike a metal target, they produce X-rays, but striking a non-metal does not necessarily produce X-rays.
Thus, option B is false.
Cathode rays are particle beams, not electromagnetic induced waves.
Therefore, option C is false.
The only correct statement is that cathode rays travel along straight lines.
Answer:Option A is correct: It travels along straight lines.