In the context of the Physical layer of the OSI model, signaling refers to the process of transmitting raw bitstreams over a physical medium. This involves the electrical, optical, or radio frequency signals that represent binary data, as well as the specifications for how those signals are generated, transmitted, and received.
Thus, the best description among the options you may be considering would relate to the transmission of data as electrical, optical, or radio signals, rather than file organization or routing. If you provide me with more options, I can help you select the most appropriate one.