Read this and answer the question. If the question is unanswerable, say "unanswerable".

In 1579 the northern seven provinces signed the Union of Utrecht, in which they decided to join forces against Spanish rule. The Union of Utrecht is seen as the beginning of the Dutch Republic. In 1580 the new and predominantly Protestant state abolished the bishoprics, including the archbishopric of Utrecht. The stadtholders disapproved of the independent course of the Utrecht bourgeoisie and brought the city under much more direct control of the republic; which shifted the power towards its dominant province Holland. This was the start of a long period of stagnation of trade and development in Utrecht. Utrecht remained an atypical city in the new republic with about 40% Catholic in the mid-17th century, and even more among the elite groups, who included many rural nobility and gentry with town houses there.

What union ended the Dutch Republic?
unanswerable