To what number have Sinn Fein's seats increased from 1998 to 2017?

The correct answer reflects the significant growth in representation for Sinn Féin in the Northern Ireland Assembly over the specified time period. From 1998, when Sinn Féin had approximately 18 seats, their representation increased to 27 seats by 2017, showcasing a notable rise in their influence and support among the electorate.

This increase can be attributed to various factors, including shifts in public opinion, changes in electoral strategy, and the impact of socio-political dynamics in Northern Ireland. The growth in seats highlights Sinn Féin's strengthened position and the increasing acceptance of their agenda among voters during this period.

The other options do not accurately capture the extent of Sinn Féin's growth within the Assembly, underselling the party's significant electoral gains and their evolving role in Northern Irish politics.