What is one of the primary characteristics of CRT monitors?

One of the primary characteristics of CRT (Cathode Ray Tube) monitors is that they rely on electron beams for image creation. The technology behind CRT monitors involves firing electron beams from the cathode ray tube onto a phosphorescent screen. When these beams hit the screen, they light up in different colors depending on the specific phosphors used, thereby forming the images that we see. This method of image creation is fundamental to how CRT displays operate, distinguishing them from other types of monitors like LCDs and LEDs, which do not utilize electron beams but rather liquid crystals or light-emitting diodes.

The other options represent different technologies and characteristics that do not apply to CRT monitors. Liquid crystal displays, for example, are characteristic of LCDs, which operate based on a different principle. The lightweight and portable nature mentioned is more applicable to modern flat-panel displays, while CRT monitors are generally heavier and bulkier. Lastly, CRT monitors are not noted for extremely low energy consumption; in fact, they typically consume more power than many modern display technologies. Understanding the fundamental operation of CRT monitors helps in grasping the evolution of display technologies in computing.