Final answer:
Statistical Time Division multiplexing is the method that constructs a frame containing data only from active input sources, making it distinct from other multiplexing methods like Frequency Division and Synchronous Time Division.
Step-by-step explanation:
The correct answer is Statistical Time Division multiplexing. This method of multiplexing creates a frame that includes data only from those input sources that have data to send. Unlike Frequency Division or Synchronous Time Division, Statistical Time Division multiplexing does not allocate time slots to inputs if they have no data to transmit. Instead, it dynamically allocates bandwidth to active inputs, making it a highly efficient form of data transmission.
Dense Wavelength Division multiplexing is related to the options listed in the reference choices (a-d), which pertain to the electromagnetic spectrum's characteristics. However, Dense Wavelength Division multiplexing is not a correct answer to the given question as it pertains to multiplexing in optical fiber communications, not the handling of data frames with respect to sender activity in a network.