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

Ex Input:
What is Rayleigh scattering?, Context: 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.

Ex Output:
optical effect


Ex Input:
What did the Founding Fathers intend more of?, Context: In contrast, Europe has a greater history of unitary states than North America, thus European "federalism" argues for a weaker central government, relative to a unitary state. The modern American usage of the word is much closer to the European sense. As the power of the Federal government has increased, some people have perceived a much more unitary state than they believe the Founding Fathers intended. Most people politically advocating "federalism" in the United States argue in favor of limiting the powers of the federal government, especially the judiciary (see Federalist Society, New Federalism).

Ex Output:
limiting the powers of the federal government


Ex Input:
Why can the terrain only hold cacti and succulent plants?, Context: As the terrain is generally arid, the hills have mostly poor soil and support only cacti and succulent plants. During the rainy season the area turns green with vegetation and grass. The eastern part of the island is greener as it receives more rainfall. A 1994 survey has revealed several hundred indigenous species of plants including the naturalized varieties of flora; some growing in irrigated areas while the dry areas are dominated by the cacti variety. Sea grapes and palm trees are a common sight with mangroves and shrubs surviving in the saline coastal swamps. Coconut palm was brought to the island from the Pacific islands. Important plants noted on the island are:

Ex Output:

the terrain is generally arid