The combination of two or more signals for ECG transmission is called:

The term that describes the combination of two or more signals for ECG transmission is known as a multiplex system. Multiplexing is a technique used in communication where multiple signals are combined into one signal over a shared medium. This approach allows for efficient use of resources, enabling multiple ECG signals to be transmitted simultaneously without interference.

In biomedical applications, such as ECG monitoring, multiplexing is especially beneficial as it allows for real-time monitoring of multiple patients or multiple leads from a single patient. This process not only optimizes the bandwidth but ensures that all data can be efficiently processed and analyzed.

The other terms refer to different communication methods; for example, a simplex system allows transmission in only one direction, while a half-duplex system permits two-way communication but not simultaneously. A trunking system refers more to a method of allocating communication channels rather than the combination of signals for transmission. Therefore, multiplex is the correct answer as it directly pertains to the combination of signals within the context of ECG transmission.