Final answer:
A single strand does not have a regular and uniform diameter or an irregular and varying diameter. It does not maintain any shape and cannot have a diameter. Therefore, the characteristic of a single strand is that it has no diameter.
Step-by-step explanation:
A single strand does not have a regular and uniform diameter or an irregular and varying diameter. It does not maintain any shape and cannot have a diameter. Therefore, the characteristic of a single strand is that it has no diameter.