3. The fundamental sign to distinguish between old and new things is ().

I'll choose A if I choose a radio station, and I'll choose AD if I choose multiple radio stations.

Because new things are not necessarily correct things, history has proved that traditional things and earlier truths are misunderstood as fallacies in a certain process, but there are also many examples that will be re-recognized after a period of time. So I think the only fundamental sign to distinguish the old from the new is time.