[求助]GWD-12-Q3哦~

GWD-12-Q3:

Were it not for the fusion-powered heat and radiation that rush from its core, instead its own weight would cause a star to collapse.

A.     instead its own weight would cause a star to collapse

B.      instead a star would have collapsed under its own weight

C.     a star would have to be collapsing under its own weight

D.     a star would collapse under its own weight

E.      its own weight would have caused a star’s collapse

答案是D，我选了A...不太明白画线句子前面的结构，是倒装了么~？

谢谢啦~