What does 'signal propagation delay' indicate?

Signal propagation delay is a critical concept in networking that describes the time it takes for a signal to travel from the sender to the receiver. This delay is influenced by the distance between the two points and the medium through which the signal travels, such as copper wire, fiber optics, or wireless channels. Understanding signal propagation delay is essential for evaluating the performance and efficiency of a network, especially in systems where response time is crucial, such as real-time communication or streaming applications.

The other options address different aspects of network performance. Network encryption may introduce latency, but this is not what signal propagation delay specifically refers to. Connection establishment time relates to the process required to set up a session for communication, which is separate from the actual travel time of a signal. Data processing time in a terminal involves the delay caused by hardware and software processing, rather than the physical distance a signal must travel. Thus, the definition provided in option B accurately captures the essence of signal propagation delay.