It can be inferred from the passage that the argument in favor of the model described in the hightlighted portion would be strengthened if which of the following were found to be true? A. Episodes of intense volcanic eruptions in the distant past occurred in cycles having very long periodicities. B. At the present time the global level of thunderstorm activity increases and decreases in cycles with periodicities of approximately 11 years. C. In the distant past cyclical climatic changes had periodicities of longer than 200 years. D. In the last century the length of the sunspot cycle has been known to vary by as much as 2 years from its average periodicity of 11 years. E. Hundreds of millions of years ago. solar-activity cycles displayed the same periodicities as do present-day solar-activity cycles.