GMAT Sentence Correction (SC) | Re: Until recently, trade flows were of interest mainly to economic expert

Until recently, trade flows were of interest mainly to economic experts and executives of large corporations, butsince the past few years, the movement of goods and services across national boundaries have become the subject of intense public attention all over the world.

In all the options, we have a time frame -> Since or over. A very good indication that we require a present perfect tense here.
Also, "the movement" is a particular movement and should be singular.

A. since the
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