Help, xdf-S11-T21 , sentence structure and meaning

isuffering

21. The filibuster, a parliamentary device that slows the
snail's pace that prevails even in the best of times in
congressional sessions and tests the endurance of
everyone associated with it, seems more and more
an anachronism in the age of telecommunications.

I'm not sure about the meaning and the structure of the ",..., " part of the sentence.

here, is the structure

, a parliamentary device
that slows (the snail's pace that prevails even in the best of times in congressional sessions )
and tests( the endurance of everyone associated with it),

i.e.
a parliamentary device that slows and tests

or

, a parliamentary device that slows the snail's pace
that prevails( even in the best of times in congressional sessions)
and tests( the endurance of everyone associated with it),

i.e.
the snail's pace that prevails and tests


I want to make clear the structure and the meaning of the ",...,"part of the sentence ?

Can any NN help?

Thanks in advance.

[此贴子已经被作者于2003-8-1 10:17:21编辑过]

isuffering

Looking forawrd to your discussion.

[此贴子已经被作者于2003-8-1 10:20:02编辑过]

QY

I think the first explaination is better.

pace that test ... with it is not reasonable

mindfree

...device that slows ...and tests...

It is the meaning that determines the structure.

isuffering

QY and Mindfree,

A lot thanks.

I agree with you.

Now I'm sure that one so-called authority Gmat SC teacher made a mistake since he analysed it as the second structure.