What occurs in the wavelength division multiplexing (WDM) process?

Wavelength Division Multiplexing (WDM) is a technology that allows multiple signals to be transmitted simultaneously over a single optical fiber by assigning each signal a different wavelength, or color, of light. In this process, the optical outputs from multiple lasers that operate at different wavelengths are combined into a single beam of light. This combined signal can then be transported over the fiber without interference between the different wavelengths.

Using different wavelengths to carry different signals significantly increases the capacity of the fiber for data transmission. This approach makes efficient use of the fiber's bandwidth and allows for improved overall network performance, as multiple channels can operate concurrently.

Other options describe different scenarios that do not accurately reflect the WDM process. For example, having multiple light sources be separated does not leverage the combined capacity that WDM offers. Transmitting only one wavelength at a time contradicts the core concept of WDM, which is to utilize multiple wavelengths simultaneously. Amplifying signals separately may be necessary for certain applications, but it does not characterize the fundamental operation of WDM itself. Thus, option C correctly encapsulates the essence of WDM technology.