TASK DEFINITION: This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.
PROBLEM: In the Western Balkans, South Slavs and Germanic Gepids intermarried with Avar invaders, eventually producing a Slavicized population.[citation needed] In Central Europe, the Slavs intermixed with Germanic and Celtic, while the eastern Slavs encountered Uralic and Scandinavian peoples. Scandinavians (Varangians) and Finnic peoples were involved in the early formation of the Rus' state but were completely Slavicized after a century. Some Finno-Ugric tribes in the north were also absorbed into the expanding Rus population. At the time of the Magyar migration, the present-day Hungary was inhabited by Slavs, numbering about 200,000, and by Romano-Dacians who were either assimilated or enslaved by the Magyars. In the 11th and 12th centuries, constant incursions by nomadic Turkic tribes, such as the Kipchaks and the Pechenegs, caused a massive migration of East Slavic populations to the safer, heavily forested regions of the north. In the Middle Ages, groups of Saxon ore miners settled in medieval Bosnia, Serbia and Bulgaria where they were Slavicized.

SOLUTION: Where did South Slavs and Germanic Gepids intermarried with Avar invaders?

PROBLEM: In the early 19th century, the Indigenous American woman Sacagawea, who would help translate for and guide the Lewis and Clark Expedition in the West, married the French trapper Toussaint Charbonneau. Most marriages between Europeans and Indigenous Americans were between European men and Indigenous American women. Depending on the kinship system of the woman's tribe, their children would be more or less easily assimilated into the tribe. Nations that had matrilineal systems, such as the Creek and Cherokee in the Southeast, gave the mixed-race children status in their mother's clans and tribes. If the tribe had a patrilineal system, like the Omaha, the children of white fathers were considered white. Unless they were specifically adopted into the tribe by an adult male, they could have no social status in it.

SOLUTION: Who married Sacagewea?

PROBLEM: The purpose of these instruments was to address the various forms of corruption (involving the public sector, the private sector, the financing of political activities, etc.) whether they had a strictly domestic or also a transnational dimension. To monitor the implementation at national level of the requirements and principles provided in those texts, a monitoring mechanism – the Group of States Against Corruption (also known as GRECO) (French: Groupe d'Etats contre la corruption) was created.

SOLUTION:
What does GRECO stand for?