The probition found in Anglo-Saxon texts against

The prohibition found in Anglo-Saxon texts against holding meetings in buildings so that individuals wouldn't be subject to the influence of magic is surely an outcome of the prejudices existing in favor of keeping up old customs - specifically, tribal rituals. Folk tales, which record important recollections of the tribe, tell that tribal meetings were customarily held in the open air.

In the passage above, the author develops the argument by _________________ .

A. refuting the plausibility of evidence that supports the opponent's argument
B. introducing evidence to support a conclusion drawn earlier in the passage
C. explaining the effects of new customs on our interpretation of present-day law
D. qualifying an implied assumption with a related anecdote
E. revealing differences between customs that were previously thought to be related

After five responses, I'll post the OA. Thanks.