SAT Question 505054e3: Form Structure And Sense answer and explanation

English - Form Structure And Sense - Finite And Nonfinite Verb Forms
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In the eastern Chinese city of Suzhou, known as a hub for silk manufacturing, a unique tradition of embroidery ______ back over two thousand years—one that includes iconic double-sided stitching with different images on each side—remains popular with modern audiences, preserving the city’s cultural heritage.
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Difficulty:Hard
Which choice completes the text so that it conforms to the conventions of Standard English?