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

To map Earth's interior, geologists use a network of seismometers to chart seismic waves that originate in the earth's crust and ricochet around its interior, most rapidly traveling through cold. dense regions and slower through hotter rocks.

A. interior, most rapidly traveling through cold, dense regions andslower - "rapidly" not parallel to "slower"
B. interior, which travel most rapidly through cold, dense regions, and more slowly - "rapidly" parallel to "slowly"
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