Geologists have found that streams in the Great basin

[750plus]

Dear Team at Manhattan,

The question that I'm posting already has a thread running but as per Mr. Purewal' direction that thread is in the wrong folder. Since this is a GMAT Prep question so I'm creating a new thread in the right folder.

This question appears in the Paid Question Pack so I'm not completely reproducing the same problem here. Rather, I am just asking the doubt that I have.

Geologists have found that streams in the Great basin of North America changed suddenly 200 million years ago, shifting from the meandering shape typically found in well-vegetated zones to the braided pattern found in areas where it is without deep-rooted vegetation for holding the soil together.

I just want to know whether the usage of the Verb-ing ' shifting ' is correct here?

This is what I think. Please confirm my reasoning.

Shifting is used correctly as it qualifies streams as the subject and describes how streams in the Great basin of North America changed suddenly [ Working correctly as an adverbial modifier ]

Warm Regards

[RonPurewal]

yeah, but it's redundant (its meaning is already present in "changed").

[RonPurewal]

by the way, i was liberal enough to answer this one, but, a banned source is a banned source.

'banned' does not mean 'reproduce only one answer choice'; 'banned' means banned.

thank you.