Since 1989, after the Berlin Wall had been demolished, one of the most problematic ethnic groups in the reunified Germany, in cultural and economic assimilation terms, were the former East Germans, who have had to acclimate to an entirely different political system.

A] after the Berlin Wall had been demolished, one of the most problematic ethnic groups in the reunified German, in cultural and economic assimilation terms, were the former East Germans.

B] after the Berlin Wall was demolished, one of the most problematic ethnic groups in the reunified Germany, in cultural terms as well as those of economic assimilation, were the former East Germans.

C] when the Berlin Wall was demolished, one of the reunified Germany's most problematic ethnic groups, in terms of cultural and economic assimilation, was the former East Germans

D] when the Berlin Wall was demolished, one of the most problematic ethnic groups in the reunified Germany, in terms of cultural and economic assimilation, has been the former East Germans.

E] after the Berlin Wall had been demolished, one of the most problematic ethnic groups in the reunified Germany, in both terms of cultural and economic assimilation, have been the former East Germans.


[spoiler]OA is D>[/spoiler]

Two things tested here, one is the numerical idioms and the second is the Redundancy.

In case of redundancy, 'one of the' is always singular or depends on the noun. Ethnic groups in Germany is plural so they should use a plural verb. But that is not happening, and a singular verb is used. That means 'one of the' is always singular.

Second, the beginning of the sentence is 'Since 1989' and then the use of the word 'after' is not correct. Since 1989 already means after 1989 and so the usage of 'when' is more preferable. Hence the case of redundancy.

So it comes down to the options C and D, C is very awkward and inconcise. Therefore the OA is D.


Kindly see the explanation and rectify in case of my mistake. Thank You,