What is the distinguishing feature between a red light and a yield signal?

The correct choice highlights that the distinguishing feature between a red light and a yield signal is the presence of islands or channels. A red light typically indicates that vehicles must come to a complete stop, and the intersection may not be designed to facilitate additional traffic flows alongside it. Yield signals, on the other hand, are often located in contexts where drivers are expected to slow down and be prepared to stop, allowing other vehicles or pedestrians to proceed.

In many instances, yield signals are placed at intersections with physical features such as channeling islands, which guide traffic more smoothly and direct the flow, allowing for a combination of merging and yielding without necessarily having to come to a complete stop, unlike a solid red light. This helps to manage traffic efficiently in areas where stopping completely may not be necessary.

The other choices, such as color intensity, shape of the signal, or position of the signal, do not adequately capture the functional differences and traffic management principles implied by the presence of these signals. Color intensity and signal shape relate more to basic traffic signal recognition, while position can vary based on roadway design and does not specifically denote the operational responsibilities of those signals.