Commentator: In many countries the influence of fringe movements is increasing. The great centrifugal engine of mode...

Victoria on May 13, 2019

Hello @wills,

We are looking for an answer choice that weakens the commentator's argument.

B is the correct answer in this case as it contradicts the commentator's conclusion that national identities are threatened by modern culture. If a stable national identity is typically a composite of a large number of subcultures, then modern culture would support rather than threaten national identities.

B and D are similar in that they both discuss the concept of pluralistic cultures; however, D takes a stance, claiming that pluralistic national cultures are preferable to monolithic national cultures. In the passage, the commentator is simply claiming that modern culture threatens current national identities. They do not take a stance on this supposed replacement of monolithic national cultures with pluralistic national cultures. They are simply stating the conclusion that they have reached based on the evidence that modern culture is quickly producing new ideologies etc., and that these fringe movements are becoming more influential.
It is also significant to note that my explanation of D above conflates "national culture" and "national identity." It is unclear whether the commentator believes that the two are one and the same or not.

Hope this is helpful! Let us know if you have any further questions.