TASK DEFINITION: In this task, you are given a question and a context passage. You have to answer the question based on the given passage.
PROBLEM: Why are areas in Neolithic sudan no longer settled?, Context: During the Neolithic Era, before the onset of desertification, around 9500 BCE the central Sudan had been a rich environment supporting a large population ranging across what is now barren desert, like the Wadi el-Qa'ab. By the 5th millennium BCE, the people who inhabited what is now called Nubia, were full participants in the "agricultural revolution", living a settled lifestyle with domesticated plants and animals. Saharan rock art of cattle and herdsmen suggests the presence of a cattle cult like those found in Sudan and other pastoral societies in Africa today. Megaliths found at Nabta Playa are overt examples of probably the world's first known archaeoastronomy devices, predating Stonehenge by some 2,000 years. This complexity, as observed at Nabta Playa, and as expressed by different levels of authority within the society there, likely formed the basis for the structure of both the Neolithic society at Nabta and the Old Kingdom of Egypt.

SOLUTION: now barren desert

PROBLEM: what is the second time period mentioned?, Context: European colonialism in the Sahara began in the 19th century. France conquered the regency of Algiers from the Ottomans in 1830, and French rule spread south from Algeria and eastwards from Senegal into the upper Niger to include present-day Algeria, Chad, Mali then French Sudan including Timbuktu, Mauritania, Morocco (1912), Niger, and Tunisia (1881). By the beginning of the 20th century, the trans-Saharan trade had clearly declined because goods were moved through more modern and efficient means, such as airplanes, rather than across the desert.

SOLUTION: 1830

PROBLEM: What is a good reference for international Georgian architecture design?, Context: Unlike the Baroque style that it replaced, which was mostly used for palaces and churches, and had little representation in the British colonies, simpler Georgian styles were widely used by the upper and middle classes. Perhaps the best remaining house is the pristine Hammond-Harwood House (1774) in Annapolis, Maryland, designed by the colonial architect William Buckland and modelled on the Villa Pisani at Montagnana, Italy as depicted in Andrea Palladio's I quattro libri dell'architettura ("Four Books of Architecture").

SOLUTION:
Andrea Palladio's I quattro libri dell'architettura