In this task, you are given a question and a context passage. You have to answer the question based on the given passage.

[EX Q]: 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.
[EX A]: now barren desert

[EX Q]: Glass that has been covered with ash or soot on one one side to obscure light is called?, Context: Historically, pubs have been socially and culturally distinct from cafés, bars and German beer halls. Most pubs offer a range of beers, wines, spirits, and soft drinks and snacks. Traditionally the windows of town pubs were of smoked or frosted glass to obscure the clientele from the street but from the 1990s onwards, there has been a move towards clear glass, in keeping with brighter interiors.
[EX A]: smoked

[EX Q]: What is the ultimate goal of Zen Buddhism?, Context: Zen Buddhism (禅), pronounced Chán in Chinese, seon in Korean or zen in Japanese (derived from the Sanskrit term dhyāna, meaning "meditation") is a form of Buddhism that became popular in China, Korea and Japan and that lays special emphasis on meditation.[note 12] Zen places less emphasis on scriptures than some other forms of Buddhism and prefers to focus on direct spiritual breakthroughs to truth.
[EX A]:
truth