分词作伴随状语与作定语的区别？

One noted economist has made a comparison of the Federal Reserve and an automobile as racing through a tunnel, bouncing first off one wall, then the other: the car may get where it is going, but people may be hurt in the process.

(A) made a comparison of the Federal Reserve and an automobile as racing through a tunnel, bouncing

(B) made a comparison between the Federal Reserve and an automobile racing through a tunnel, bouncing

(C) compared the federal Reserve with an automobile as racing through a tunnel and which bounced

(D) compared the Federal Reserve to an automobile racing through a tunnel, bouncing（D）

(E) compared the Federal Reserve with an automobile that races through a tunnel and it bounces

答案是D我没有疑问，但有疑问的是，这里的bouncing 是作伴随状语还是作定语修饰automatic？我觉得是做定语。但如何区别作定语还是做状语呢？

逗号后的现分一般优先考虑做状语