GMAT Sentence Correction (SC) | Re: To map Earth's interior, geologists use a network of seismometers to

Hi expert,
I would like ask for your thought about option B.
In my 2 cents,"which" could rightly modifies seismic waves.What's wrong is that we now have two modifiers back-to-back--"that originate...," and "which travel most ...".

Is my reasoning correct?
Also,if we want to modifies the same thing,do we always have to use the same relative pronoun--either both "that" or both "which"?

Thanks

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