In this task, you're expected to write answers to questions involving multiple references to the same entity. The answer to the question should be unambiguous and a phrase in the paragraph. Most questions can have only one correct answer.

Passage: Manchester has a notable place in the history of Marxism and left-wing politics; being the subject of Friedrich Engels' work The Condition of the Working Class in England in 1844; Engels spent much of his life in and around Manchester, and when Karl Marx visited Manchester, they met at Chetham's Library. The economics books Marx was reading at the time can be seen in the library, as can the window seat where Marx and Engels would meet. The first Trades Union Congress was held in Manchester (at the Mechanics' Institute, David Street), from 2 to 6 June 1868. Manchester was an important cradle of the Labour Party and the Suffragette Movement.At that time, it seemed a place in which anything could happennew industrial processes, new ways of thinking (the Manchester School, promoting free trade and laissez-faire), new classes or groups in society, new religious sects, and new forms of labour organisation. It attracted educated visitors from all parts of Britain and Europe. A saying capturing this sense of innovation survives today: "What Manchester does today, the rest of the world does tomorrow." Manchester's golden age was perhaps the last quarter of the 19th century. Many of the great public buildings (including Manchester Town Hall) date from then. The city's cosmopolitan atmosphere contributed to a vibrant culture, which included the Halle Orchestra. In 1889, when county councils were created in England, the municipal borough became a county borough with even greater autonomy.
Although the Industrial Revolution brought wealth to the city, it also brought poverty and squalor to a large part of the population. Historian Simon Schama noted that "Manchester was the very best and the very worst taken to terrifying extremes, a new kind of city in the world; the chimneys of industrial suburbs greeting you with columns of smoke". An American visitor taken to Manchester's blackspots saw "wretched, defrauded, oppressed, crushed human nature, lying and bleeding fragments".The number of cotton mills in Manchester itself reached a peak of 108 in 1853. Thereafter the number began to decline and Manchester was surpassed as the largest centre of cotton spinning by Bolton in the 1850s and Oldham in the 1860s. However, this period of decline coincided with the rise of the city as the financial centre of the region. Manchester continued to process cotton, and in 1913, 65% of the world's cotton was processed in the area. The First World War interrupted access to the export markets. Cotton processing in other parts of the world increased, often on machines produced in Manchester. Manchester suffered greatly from the Great Depression and the underlying structural changes that began to supplant the old industries, including textile manufacture.
Question: What place attracted educated visitors from all parts of Britain and Europe?
Manchester.

Passage: By the late 1950s, Covent Garden was gradually abandoning its policy of productions in the vernacular; such singers as Maria Callas would not relearn their roles in English. This made it easier for Tucker to point up the difference between the two London opera companies. While Covent Garden engaged international stars, Sadler's Wells focused on young British and Commonwealth performers. Colin Davis was appointed musical director in succession to Gibson in 1961. The repertoire continued to mix familiar and unfamiliar operas. Novelties in Davis's time included Pizzetti's Murder in the Cathedral, Stravinsky's Oedipus rex, Richard Rodney Bennett's The Mines of Sulphur and more Janacek. Sadler's Wells's traditional policy of giving all operas in English continued, with only two exceptions: Oedipus rex, which was sung in Latin, and Monteverdi's L'Orfeo, sung in Italian, for reasons not clear to the press. In January 1962, the company gave its first Gilbert and Sullivan opera, Iolanthe, on the day on which the Savoy operas came out of copyright and the D'Oyly Carte monopoly ended. The production was well received (it was successfully revived for many seasons until 1978) and was followed by a production of The Mikado in May of the same year.The Islington theatre was by now clearly too small to allow the company to achieve any further growth. A study conducted for the Arts Council reported that in the late 1960s the two Sadler's Wells companies comprised 278 salaried performers and 62 guest singers. The company had experience of playing in a large West End theatre, such as its 1958 sell-out production of The Merry Widow that had transferred to the 2,351-seat London Coliseum for a summer season. Ten years later, the lease of the Coliseum became available. Stephen Arlen, who had succeeded Tucker as managing director, was the primary advocate for moving the company. After intense negotiations and fund-raising, a ten-year lease was signed in 1968. One of the company's last productions at the Islington theatre was Wagner's The Mastersingers, conducted by Goodall in 1968, which 40 years later was described by Gramophone magazine as "legendary". The company left Sadler's Wells with a revival of the work with which it had re-opened the theatre in 1945, Peter Grimes. Its last performance at the Rosebery Avenue theatre was on 15 June 1968.
Question: What are the names of the people that wrote the opera The Mikado?
Gilbert.

Passage: The impact would have caused a megatsunami over 100 metres (330 ft) tall that would have reached all the way to what are now Texas and Florida. The height of the tsunami was limited by the relatively shallow sea in the area of the impact; in deep ocean it would have been 4.6 kilometres (2.9 mi) tall. A cloud of super-heated dust, ash and steam would have spread from the crater as the impactor burrowed underground in less than a second. Excavated material along with pieces of the impactor, ejected out of the atmosphere by the blast, would have been heated to incandescence upon re-entry, broiling the Earth's surface and possibly igniting wildfires; meanwhile, colossal shock waves would have triggered global earthquakes and volcanic eruptions. Fossil evidence for an instantaneous die-off of diverse animals was found in a soil layer only 10 centimetres (3.9 in) thick in New Jersey some 5,000 kilometres (3,100 mi) away from the impact site, indicating that death and burial under debris occurred suddenly and quickly over wide distances on land.The emission of dust and particles could have covered the entire surface of the Earth for several years, possibly a decade, creating a harsh environment for living things. The shock production of carbon dioxide caused by the destruction of carbonate rocks would have led to a sudden greenhouse effect. Over a decade or longer, sunlight would have been blocked from reaching the surface of the Earth by the dust particles in the atmosphere, cooling the surface dramatically. Photosynthesis by plants would also have been interrupted, affecting the entire food chain. A model of the event developed by Lomax et al. (2001) suggests that net primary productivity (NPP) rates may have increased to higher than pre-impact levels over the long term because of the high carbon dioxide concentrations.In February 2008, a team of researchers led by Sean Gulick at the University of Texas at Austin's Jackson School of Geosciences used seismic images of the crater to determine that the impactor landed in deeper water than was previously assumed. They argued that this would have resulted in increased sulfate aerosols in the atmosphere. According to the press release, that "could have made the impact deadlier in two ways: by altering climate (sulfate aerosols in the upper atmosphere can have a cooling effect) and by generating acid rain (water vapor can help to flush the lower atmosphere of sulfate aerosols, causing acid rain)." This was borne out by the results of a drilling project in 2016 which found that sulfate-containing rocks found in the area were not found in the peak ring (the rocks found were from deep within the earth's crust instead), the interpretation being that they had been vaporized by the impact and dispersed into the atmosphere.
Question: What is the full name of what NPP stands for?
net primary productivity.