What Has Been an Important Source of Conflict in Northern

What has been an important source of conflict in Northern Ireland?

A) The Protestant minority feel that the Catholic minority has discriminated against them.
B) The Catholic minority feel that the Protestant majority has discriminated against them.
C) The northern Irish want all of the road signs and other public documents printed in their native Celtic language.
D) There is a large influx of foreign immigration every year.
E) There is a proposed constitutional amendment prohibiting same-sex marriage.