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]: 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 A]: optical effect

[EX Q]: What students is City of Bath School limited to?, Context: Some of the county's secondary schools have specialist school status. Some schools have sixth forms and others transfer their sixth formers to colleges. Several schools can trace their origins back many years, such as The Blue School in Wells and Richard Huish College in Taunton. Others have changed their names over the years such as Beechen Cliff School which was started in 1905 as the City of Bath Boys' School and changed to its present name in 1972 when the grammar school was amalgamated with a local secondary modern school, to form a comprehensive school. Many others were established and built since the Second World War. In 2006, 5,900 pupils in Somerset sat GCSE examinations, with 44.5% achieving 5 grades A-C including English and Maths (compared to 45.8% for England).
[EX A]: Boys

[EX Q]: What category of organism has the restriction modification system?, Context: It is likely that a multicomponent, adaptive immune system arose with the first vertebrates, as invertebrates do not generate lymphocytes or an antibody-based humoral response. Many species, however, utilize mechanisms that appear to be precursors of these aspects of vertebrate immunity. Immune systems appear even in the structurally most simple forms of life, with bacteria using a unique defense mechanism, called the restriction modification system to protect themselves from viral pathogens, called bacteriophages. Prokaryotes also possess acquired immunity, through a system that uses CRISPR sequences to retain fragments of the genomes of phage that they have come into contact with in the past, which allows them to block virus replication through a form of RNA interference. Offensive elements of the immune systems are also present in unicellular eukaryotes, but studies of their roles in defense are few.
[EX A]:
bacteria