What political solution to Irish independence demands resulted in part from Sinn Féin members refusing to sit in Parliament?

A) British recognition of an independent,unified Ireland
B) British police attacks on Irish civilians
C) the start of increased fighting,known as "The Troubles"
D) a ban on Irish political participation
E) the division of Ireland between the Catholic South and Protestant North

Sinn Féin members refused to sit in the British Parliament in Northern Ireland and instead established their own parliament in Dublin, advocating for a united Ireland. This ultimately led to the division of Ireland in 1921, creating the independent Republic of Ireland in the south and the six predominantly Protestant counties of Northern Ireland remaining part of the United Kingdom. This arrangement has been a major point of contention and violence in Irish history and is often referred to as "The Troubles."