A wave of unusual violence, from murder to suicide, plagued a medieval

A wave of unusual violence, from murder to suicide, plagued a medieval town for a period of five years. Concurrently, there was an unusual shift in the area's weather: rainfall was so heavy and continuous that the rye crop probably fell prey to the ergot fungus, which causes those who eat it to develop a psychosis-inducing disease called ergotism. In the end, we can conclude that the town's violence was the result of freakish weather conditions.

Which of the following is the most effective rebuttal to the conclusion made above?

-It is based on a series of plausible suppositions rather than upon contemporary evidence.
-No clear distinction is drawn between cause and effect.
-Explanations of historical events cannot be convincing when too great a role is assigned to chance or the irrational.
-The author relies too heavily on probable occurrences instead of actual occurrences.
-Such crucial terms as "unusual violence" are not adequately defined in regard to the specific historical event.

+1 Kudos if you like the question and if you want the OE . this is from Kaplan and the OA is indeed correct!