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In nature, the red color of blood comes from hemoglobin, the iron-containing protein found in the red blood cells of all vertebrates. The red color of the Grand Canyon and other geological features is caused by hematite or red ochre, both forms of iron oxide. It also causes the red color of the planet Mars. The red sky at sunset and sunrise is caused by an optical effect known as Rayleigh scattering, which, when the sun is low or below the horizon, increases the red-wavelength light that reaches the eye. The color of autumn leaves is caused by pigments called anthocyanins, which are produced towards the end of summer, when the green chlorophyll is no longer produced. One to two percent of the human population has red hair; the color is produced by high levels of the reddish pigment pheomelanin (which also accounts for the red color of the lips) and relatively low levels of the dark pigment eumelanin.
What pigment is responsible for the color of leaves in fall?
A: anthocyanins

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There is a close connection between machine learning and compression: a system that predicts the posterior probabilities of a sequence given its entire history can be used for optimal data compression (by using arithmetic coding on the output distribution) while an optimal compressor can be used for prediction (by finding the symbol that compresses best, given the previous history). This equivalence has been used as a justification for using data compression as a benchmark for "general intelligence."
What type of compressor can be used for general intelligence?
A: unanswerable

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In ancient China, early literature was primarily focused on philosophy, historiography, military science, agriculture, and poetry. China, the origin of modern paper making and woodblock printing, produced one of the world's first print cultures. Much of Chinese literature originates with the Hundred Schools of Thought period that occurred during the Eastern Zhou Dynasty (769-269 BCE). The most important of these include the Classics of Confucianism, of Daoism, of Mohism, of Legalism, as well as works of military science (e.g. Sun Tzu's The Art of War) and Chinese history (e.g. Sima Qian's Records of the Grand Historian). Ancient Chinese literature had a heavy emphasis on historiography, with often very detailed court records. An exemplary piece of narrative history of ancient China was the Zuo Zhuan, which was compiled no later than 389 BCE, and attributed to the blind 5th century BCE historian Zuo Qiuming.
What historic period was the foundry for classic Chinese literature in the ancient world?
A: the Hundred Schools of Thought period

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The city is also home to two large colleges. The City College Plymouth provides courses from the most basic to Foundation degrees for approximately 26,000 students. Plymouth College of Art offers a selection of courses including media. It was started 153 years ago and is now one of only four independent colleges of art and design in the UK.
About how many students are enrolled at City College Plymouth?
A:
26,000