Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
Shell's primary business is the management of a vertically integrated oil company. The development of technical and commercial expertise in all stages of this vertical integration, from the initial search for oil (exploration) through its harvesting (production), transportation, refining and finally trading and marketing established the core competencies on which the company was founded. Similar competencies were required for natural gas, which has become one of the most important businesses in which Shell is involved, and which contributes a significant proportion of the company's profits. While the vertically integrated business model provided significant economies of scale and barriers to entry, each business now seeks to be a self-supporting unit without subsidies from other parts of the company.
What is the least important business for Shell?
A: unanswerable

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Green is common in nature, as many plants are green because of a complex chemical known as chlorophyll, which is involved in photosynthesis. Chlorophyll absorbs the long wavelengths of light (red) and short wavelengths of light (blue) much more efficiently than the wavelengths that appear green to the human eye, so light reflected by plants is enriched in green. Chlorophyll absorbs green light poorly because it first arose in organisms living in oceans where purple halobacteria were already exploiting photosynthesis. Their purple color arose because they extracted energy in the green portion of the spectrum using bacteriorhodopsin. The new organisms that then later came to dominate the extraction of light were selected to exploit those portions of the spectrum not used by the halobacteria.
What does chlorophyll do with long (red) and short (blue) wavelengths of light?
A: absorbs

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At the end of World War II Soviet troops occupied southern Sakhalin Island and the Kuril Islands, making them part of the RSFSR. The status of the southernmost Kurils remains in dispute with Japan.
Along with Sakhalin Island, what islands were occupied by the Soviets after the First World War?
A: unanswerable

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The build was released for download later in the day in standard 32-bit and 64-bit versions, plus a special 64-bit version which included SDKs and developer tools (Visual Studio Express and Expression Blend) for developing Metro-style apps. The Windows Store was announced during the presentation, but was not available in this build. According to Microsoft, there were about 535,000 downloads of the developer preview within the first 12 hours of its release. Originally set to expire on March 11, 2012, in February 2012 the Developer Preview's expiry date was changed to January 15, 2013.
How many downloads occured in the first 21 hours?
A:
unanswerable