Bunuel
Although the gig economy remains modest—employing a small fraction of the nation’s workers, according to recent studies at several leading think tanks—the technologies that power them are likely to disrupt the American labor market at an increasing rate.
(A) Although the gig economy remains modest—employing a small fraction of the nation’s workers, according to recent studies at several leading think tanks—the technologies that power them are
(B) Because the gig economy remains modest—it employs a small fraction of the nation’s workers, according to recent studies at several leading think tanks—the technologies powering them are
(C) Because the gig economy remains modest—employing a small fraction of the nation’s workers, according to recent studies at several leading think tanks—the technologies powering it is
(D) Although the gig economy remains modest—employing a small fraction of the nation’s workers, according to recent studies at several leading think tanks—the technologies powering it are
(E) With the gig economy remaining modest—it employs a small fraction of the nation’s workers, according to recent studies at several leading think tanks—the technology that powers them is
Veritas Prep Official Explanation
This problem serves you two major decision points: the decision between "it" and "them" as a pronoun, and the decision between "is" and "are" as the verb. And, importantly, the two do not modify the same noun.
The pronoun "it/them" is a stand-in for "the gig economy." You can ask yourself "what is being powered by technology" and the only logical referent is that gig economy. Therefore, with a singular referent you need the singular pronoun "it."
The verb "is/are" belongs to the subject "technologies." Because of that, you need a plural verb "are." (Note that choice E changes that subject to the singular "technologies" but has the incorrect pronoun "them" and can therefore be eliminated without consideration of the verb.)
The only sentence that properly pairs "it" (for the gig economy) with "are" (for technologies) is answer choice D, the correct answer.