(E) outlining the specific reasons why a long standing problem in solar physics is thought to be soluble at last 22. Which of the following statements concerning the comparison between pre- industrial and post-industrial climate change, as described in the passage, is accurate

A． The pre-industrial period experienced a much greater degree of climate change, owing to solar activity.
B． The post-industrial period experienced a much greater degree of climate change, owing to greenhouse gases.
C． Both periods have experienced a degree of change, but their primary causes are different.
D． Both periods have experienced a degree of change, and their primary causes are identical.
E． Scientists have yet to prove that climate change is linked to either sunspots or greenhouse gases.