SC（中国問題より３）

どなたか下記のSCの解説お願いします。

A recent study of ancient clay deposits has provided new evidence （supporting the theory of global forest ignited by a meteorite impact that） contributed to the extinction of the dinosaurs and many other creatures some 65 million years ago.





(1)supporting the theory of global forest fires ignited by a meteorite impact that

(2)supporting the theory that global forest fires ignited by a meteorite impact

(3)that supports the theory of global forest fires that were ignited by a meteorite impact and that

(4)in support of the theory that global forest fires were ignited by a meteorite impact and that

(5)of support for the theory of a meteorite impact that ignited global forest fires and



正解は(2)でした。

なんとなくですが（３）を回答に選びました。その後、自分でどうして（２）が正解になるのか考えてみましたがわかりませんでした。どなたか解説よろしく願いします。