Answer: B. LED screen control system.
Answer analysis: When discussing the various components that make up the LED display system, we need to consider the entire process of the LED display from signal input to final display. Now, let's analyze each option one by one:
A. Video source output device: This is an important link in the LED display system, but it does not directly constitute the display system itself. Video source output devices (such as computers, cameras, DVD players, etc.) are responsible for providing video signals, but these signals need to go through a certain transmission and control system before they can finally be displayed on the LED display.
B. LED screen control system: This system is responsible for receiving signals from video source output devices and converting them into a format that the LED display can understand and display. It also includes the adjustment function of display brightness, contrast, color and other parameters, as well as possible remote control and management functions. Therefore, the LED screen control system is an indispensable part of the LED display system.
C. LED display: The display itself is of course an important part of the system, but it is only the terminal of the display system, responsible for displaying the signals processed by the control system in the form of images or videos. Without the support of the control system, the display cannot work properly.
D. Power distribution system: Although the power distribution system provides power support for the entire LED display system, it itself is not a core component of the display system. The power distribution system is more like the infrastructure of the entire system, providing the necessary power guarantee for each part.
Considering the above points, we can conclude that the LED display system is composed of multiple parts, but the most core and direct parts of the system are the LED screen control system and the LED display itself. However, if you want to choose the most comprehensive and direct part of the system from the given options, then B. LED screen control system is more appropriate, because it not only includes the function of controlling the display content of the display, but also usually includes various control and management functions closely related to the display.
But it is worth noting that in actual applications, the LED display system usually includes multiple parts such as video source output devices, LED screen control systems, LED displays, and power distribution systems, which work together to achieve high-quality display effects.
Therefore, if you want to choose the parts that constitute the LED display system in a strict sense, then the more comprehensive answer should be the entire system architecture including B (LED screen control system) and C (LED display), but according to the options given in the question, B. LED screen control system is the closest answer.