IMO B
The rise in negative attitudes toward foreigners indicate that the country is becoming less tolerant, and therefore that the opportunities are ripe for extremist groups to exploit the illegal immigration problem.
(A) indicate that the country is becoming less tolerant, and therefore that -->
that the country is becoming less tolerant, and therefore
that ---> that is not needed
(B) indicates that the country is becoming less tolerant, and therefore--> CORRECT
(C) indicates that the country is becoming less tolerant, and therefore that -->
that the country is becoming less tolerant, and therefore
that ---> that is not needed
(D) indicates that the country is
being less tolerant, and therefore---> being is wrong in this context
(E) indicates that the country is becoming less tolerant of and therefore that -->
that the country is becoming less tolerant, and therefore
that ---> that is not needed