Question: Included among chromatic button accordions is what chromatic button accordion developed in Russia in the early 20th century and named after the 11th-century bard Boyan?

Context paragraphs:
Rockdale (Fallston, Maryland): Rockdale, also known as The Robinson/Stirling Place, is a historic home and farm complex located at Fallston, Harford County, Maryland, United States.  It is a farm developed from the late 18th century through the early 20th century.  The dwelling is in three parts.  The east room of the east wing is the earliest section dating from the 18th century.  The largest or main portion of the dwelling dates from between 1815 and 1830.  The north wing, a bay centered in the south façade of the second story, and a small conservatory, date from the very early 20th century.  The main house is five bays in length, two and a half stories, of stone construction, stuccoed and scored.  The home is surrounded by several outbuildings, trees, and other plantings, and the remains of formal gardens and garden structures developed in the early 20th century.  It was the residence of William E. Robinson (1860-1935), an entrepreneur in the local canning industry.

Khromka: Khromka (Russian: хро́мка , "khromka") is a type of Russian garmon (unisonoric diatonic button accordion).  It is the most widespread variant in Russia and in the former USSR.  Nearly all Russian garmons made since the mid of the 20th century are khromkas.

Architecture of Póvoa de Varzim: The architecture of Póvoa de Varzim, in Portugal, demonstrates a broad variety of architectural styles over its thousand years of history.  11th-century Romanesque, 16th-century Mannerism, 18th-century Baroque, late 18th-century neoclassicism, early 20th-century Portuguese modernism and late 20th- to early 21st-century contemporary architectural styles and more are all represented in Póvoa de Varzim.  As a whole it represents a rich eclectic tradition and innovation shaped by the people, their beliefs and economy.

Adaptationism: Adaptationism is the Darwinian view that many physical and psychological traits of organisms are evolved adaptations.  Pan-adaptationism is the strong form of this, deriving from the early 20th century modern synthesis, that all traits are adaptations, a view now shared by few biologists.  Adaptationists perform research to try to distinguish adaptations (e.g., the umbilical cord) from byproducts (e.g., the belly button) or random variation (e.g., convex or concave shape of the belly button).  George Williams' "Adaptation and Natural Selection" (1966) was highly influential in its development, defining some of the heuristics used to identify adaptations.

St Mary's Church, Reculver: St Mary's Church, Reculver, was founded in the 7th century as either a minster or a monastery on the site of a Roman fort at Reculver, which was then at the north-eastern extremity of Kent in south-eastern England.  In 669, the site of the fort was given for this purpose by King Ecgberht of Kent to a priest named Bassa, beginning a connection with Kentish kings that led to King Eadberht II of Kent being buried there in the 760s, and the church becoming very wealthy by the beginning of the 9th century.  From the early 9th century to the 10th the church was treated as essentially a piece of property, with ownership passing between kings of Mercia and Wessex and the archbishops of Canterbury.  Viking attacks may have extinguished the church's religious community in the 9th century, although an early 11th-century record indicates that the church was then in the hands of a dean accompanied by monks. By the time of Domesday Book, completed in 1086, St Mary's was serving as a parish church.

Bayan (accordion): The bayan (Russian: бая́н ; ] ) is a type of chromatic button accordion developed in Russia in the early 20th century and named after the 11th-century bard Boyan.

History of the roller coaster: Roller coaster amusement rides have origins back to ice slides constructed in 18th-century Russia.  Early technology featured sleds or wheeled carts that were sent down hills of snow reinforced by wooden supports.  The technology evolved in the 19th century to feature railroad track using wheeled cars that were securely locked to the track.  Newer innovations emerged in the early 20th century with side friction and underfriction technologies to allow for greater speeds and sharper turns.  By the mid-to-late 20th century, these elements intensified with the introduction of steel roller coaster designs and the ability for them to invert riders.

Chromatic button accordion: A chromatic button accordion is a type of button accordion where the melody-side keyboard consists of rows of buttons arranged chromatically.  The bass-side keyboard is usually the Stradella system or one of the various free-bass systems. Included among chromatic button accordions are the Russian bayan and Schrammel accordion.  There can be 3 to 5 rows of vertical treble buttons.  In a 5 row chromatic, two additional rows repeat the first 2 rows to facilitate options in fingering.

History of ecology: Ecology is a new science and considered as an important branch of biological science, having only become prominent during the second half of the 20th century.  Ecological thought is derivative of established currents in philosophy, particularly from ethics and politics.  Its history stems all the way back to the 4th century.  One of the first ecologists whose writings survive may have been Aristotle or perhaps his student, Theophrastus, both of whom had interest in many species of animals and plants.  Theophrastus described interrelationships between animals and their environment as early as the 4th century BC.  Ecology developed substantially in the 18th and 19th century.  It began with Carl Linnaeus and his work with the economy of nature.  Soon after came Alexander von Humboldt and his work with botanical geography.  Alfred Russel Wallace and Karl Möbius then contributed with the notion of biocoenosis.  Eugenius Warming’s work with ecological plant geography led to the founding of ecology as a discipline.  Charles Darwin’s work also contributed to the science of ecology, and Darwin is often attributed with progressing the discipline more than anyone else in its young history.  Ecological thought expanded even more in the early 20th century.  Major contributions included: Eduard Suess’ and Vladimir Vernadsky’s work with the biosphere, Arthur Tansley’s ecosystem, Charles Elton's "Animal Ecology", and Henry Cowles ecological succession.  Ecology influenced the social sciences and humanities.  Human ecology began in the early 20th century and it recognized humans as an ecological factor.  Later James Lovelock advanced views on earth as a macro-organism with the Gaia hypothesis.  Conservation stemmed from the science of ecology.  Important figures and movements include Shelford and the ESA, National Environmental Policy act, George Perkins Marsh, Theodore Roosevelt, Stephen A. Forbes, and post-Dust Bowl conservation.  Later in the 20th century world governments collaborated on man’s effects on the biosphere and Earth’s environment.

Second Viennese School: The Second Viennese School (German: Zweite Wiener Schule, Neue Wiener Schule ) is the group of composers that comprised Arnold Schoenberg and his pupils and close associates in early 20th century Vienna, where he lived and taught, sporadically, between 1903 and 1925.  Their music was initially characterized by late-Romantic expanded tonality and later, following Schoenberg's own evolution, a totally chromatic expressionism without firm tonal centre, often referred to as atonality; and later still, Schoenberg's serial twelve-tone technique.  Though this common development took place, it neither followed a common time-line nor a cooperative path.  Likewise, it was not a direct result of Schoenberg's teaching—which, as his various published textbooks demonstrate, was highly traditional and conservative.  Schoenberg's textbooks also reveal that the Second Viennese School spawned not from the development of his serial method, but rather from the influence of his creative example.

Supporting paragraphs: Chromatic button accordion Bayan (accordion)
Answer: bayan