Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.

Ex Input:
Context: Ryu (Ha-kyun Shin), a deaf man, works in a factory to support his ailing sister (Ji-Eun Lim) in desperate need of a kidney transplant. Ryu tries to donate one of his kidneys to his sister but is told that his blood type does not match that of his sister and so is not a suitable donor. After being laid off from his job by the factory boss, Ryu contacts a black market organ dealer who agrees to sell him a kidney suitable for his sister in exchange for 10,000,000 Korean won, plus one of Ryu's own kidneys. He takes the severance pay from his factory job and offers the money to the organ dealers, who take the money and one of his kidneys, but then disappear. Three weeks later, Ryu learns from his doctor that a kidney has been found for his sister and that the operation will cost 10,000,000 won, but since the organ dealers stole his money, he will not be able to pay for it.In need of money for the operation and in retaliation for his being fired, Ryu and his girlfriend, Yeong-mi (Doona Bae), a radical anarchist, conspire to kidnap the daughter of the boss who fired him. Instead, he realizes that the kidnapping would immediately put them under police suspicion, and they decide to kidnap Yu-sun (Bo-bae Han), the daughter of the boss's friend, Park Dong-jin (Kang-ho Song), another factory executive. The girl stays with Ryu's sister (thinking that Ryu is merely babysitting for a time), who takes care of her while the distraught Dong-jin arranges to pay her ransom. After Ryu collects the money and returns home, he learns that his sister has discovered his scheme and, unwilling to be involved or burden Ryu further, killed herself. Ryu takes Yu-sun and his sister's body into the countryside to bury her by a riverbed they used to frequent as children. While Ryu mourns, Yu-sun accidentally slips into the river and drowns.Days later, as Dong-jin mourns his daughter and swears revenge at the river bank, Ryu ambushes and murders the organ dealers. Dong-jin, having investigated the identities of the kidnappers, finds Yeong-mi and begins interrogating her. Yeong-mi apologizes for Yu-sun's death but warns him of her membership in a terrorist organization that, knowing Dong-jin's identity, will kill him if she dies. Dong-jin, unfazed by the threats, tortures her to death by electrocuting her. Ryu returns to Yeong-mi's apartment building and discovers the police removing her body on a stretcher. Ryu, consumed with grief, swears vengeance on Dong-jin.Ryu arrives at Dong-jin's residence in an attempt to kill him. He waits for some time, but Dong-Jin does not arrive: he is, in fact, waiting at Ryu's apartment. After Dong-Jin does not arrive, Ryu returns to his apartment. However, Dong-jin had previously set up an electric booby trap on his doorknob, which renders Ryu unconscious. Dong-jin then binds Ryu and returns him to the riverbed where Yu-sun died. After binding Ryu's hands and feet and bringing him chest-high into the water, an emotional Dong-jin acknowledges that although Ryu is a good man, he has no choice; Dong-jin then slashes Ryu's Achilles tendons, resulting in his drowning.Dong-jin drags Ryu back to shore and then drives off to a desolate location to bury the body. Once there, he begins to dig a hole, but soon a group of men arrives. They surround and stab Dong-jin repeatedly, finally attaching a note to his chest identifying themselves as the terrorist group of which Yeong-mi was part. The group leave Dong-jin dying beside his car with the bloody tools and bags he used to chop up, dismember, and package Ryu's body.(From Wikipedia.)
Question: How does Yu-sun die?

Ex Output:
drowns

Ex Input:
Context: Change in gene expression associated with pancreatic cancer could be attributed to the variation in histone posttranslational modifications leading to subsequent remodeling of the chromatin template during transcription. However, the interconnected network of molecules involved in regulating such processes remains elusive. hPaf1/PD2, a subunit of the human PAF-complex, involved in the regulation of transcriptional elongation has oncogenic potential. Our study explores the possibility that regulation of histone methylation by hPaf1 can contribute towards alteration in gene expression by nucleosomal rearrangement. Here, we show that knockdown of hPaf1/PD2 leads to decreased di- and tri-methylation at histone H3 lysine 4 residues in pancreatic cancer cells. Interestingly, hPaf1/PD2 colocalizes with MLL1 (Mixed Lineage Leukemia 1), a histone methyltransferase that methylates H3K4 residues. Also, a reduction in hPaf1 level resulted in reduced MLL1 expression and a corresponding decrease in the level of CHD1 (Chromohelicase DNA-binding protein 1), an ATPase dependent chromatin remodeling enzyme that specifically binds to H3K4 di and trimethyl marks. hPaf1/PD2 was also found to interact and colocalize with CHD1 in both cytoplasmic and nuclear extracts of pancreatic cancer cells. Further, reduced level of CHD1 localization in the nucleus in hPaf1/PD2 Knockdown cells could be rescued by ectopic expression of hPaf1/PD2. Micrococcal nuclease digestion showed an altered chromatin structure in hPaf1/PD2-KD cells. Overall, our results suggest that hPaf1/PD2 in association with MLL1 regulates methylation of H3K4 residues, as well as interacts and regulates nuclear shuttling of chromatin remodeling protein CHD1, facilitating its function in pancreatic cancer cells.
Question: Which is the histone residue methylated by MLL1?

Ex Output:
h3k4

Ex Input:
Context: Carbon is a very important element to living things. As the second most common element in the human body, we know that human life without carbon would not be possible. Protein, carbohydrates, and fats are all part of the body and all contain carbon. When your body breaks down food to produce energy, you break down protein, carbohydrates, and fat, and you breathe out carbon dioxide. Carbon occurs in many forms on Earth. The element moves through organisms and then returns to the environment. When all this happens in balance, the ecosystem remains in balance too. The short term cycling of carbon begins with carbon dioxide (CO2 ) in the atmosphere. Through photosynthesis, the inorganic carbon in carbon dioxide plus water and energy from sunlight is transformed into organic carbon (food) with oxygen given off as a waste product. The chemical equation for photosynthesis is: Plants and animals engage in the reverse of photosynthesis, which is respiration. In respiration, animals use oxygen to convert the organic carbon in sugar into food energy they can use. Plants also go through respiration and consume some of the sugars they produce. The chemical reaction for respiration is: C6 H12 O6 + 6 O2 6 CO2 + 6 H2 O + useable energy Photosynthesis and respiration are a gas exchange process. In photosynthesis, CO2 is converted to O2 ; in respiration, O2 is converted to CO2 . Remember that plants do not create energy. They change the energy from sunlight into chemical energy that plants and animals can use as food (Figure 1.1). Places in the ecosystem that store carbon are reservoirs. Places that supply and remove carbon are carbon sources and carbon sinks, respectively. If more carbon is provided than stored, the place is a carbon source. If more carbon dioxide is absorbed than is emitted, the reservoir is a carbon sink. What are some examples of carbon sources and sinks? Carbon sinks are reservoirs where carbon is stored. Healthy living forests and the oceans act as carbon sinks. Carbon sources are reservoirs from which carbon can enter the environment. The mantle is a source of carbon from volcanic gases. A reservoir can change from a sink to a source and vice versa. A forest is a sink, but when the forest burns it becomes a source. The amount of time that carbon stays, on average, in a reservoir is the residence time of carbon in that reservoir. Remember that the amount of CO2 in the atmosphere is very low. This means that a small increase or decrease in the atmospheric CO2 can have a large effect. By measuring the composition of air bubbles trapped in glacial ice, scientists can learn the amount of atmospheric CO2 at times in the past. Of particular interest is the time just before the Industrial Revolution, when society began to use fossil fuels. That value is thought to be the natural content of CO2 for this time period; that number was 280 parts per million (ppm). By 1958, when scientists began to directly measure CO2 content from the atmosphere at Mauna Loa volcano in the Pacific Ocean, the amount was 316 ppm (Figure 1.2). In 2014, the atmospheric CO2 content had risen to around 400 ppm. The amount of CO2 in the atmosphere has been measured at Mauna Loa Obser- vatory since 1958. The blue line shows yearly averaged CO2 . The red line shows seasonal variations in CO2 . This is an increase in atmospheric CO2 of 40% since the before the Industrial Revolution. About 65% of that increase has occurred since the first CO2 measurements were made on Mauna Loa Volcano, Hawaii, in 1958. Humans have changed the natural balance of the carbon cycle because we use coal, oil, and natural gas to supply our energy demands. Fossil fuels are a sink for CO2 when they form, but they are a source for CO2 when they are burned. The equation for combustion of propane, which is a simple hydrocarbon looks like this: The equation shows that when propane burns, it uses oxygen and produces carbon dioxide and water. So when a car burns a tank of gas, the amount of CO2 in the atmosphere increases just a little. Added over
Question: in photosynthesis, plants change this into chemical energy that plants and animals can use as food.

Ex Output:
sunlight