Question: Jonkheer Douwe Sirtema van Grovestins (Leeuwarden, Brussels, 1710 – February 26, 1778) was a Frisian courtier at the court of which stadtholder, that was the first hereditary Stadtholder of all the United Provinces?
{'answer': 'William IV, Prince of Orange-Nassau', 'supporting_facts': [['Douwe Sirtema van Grovestins', 0], ['William IV, Prince of Orange', 0]]}