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.

Input: Consider Input: Context: 1836 Komarov, provisional designation 1971 OT, is a main-belt asteroid discovered on 26 July 1971 by Nikolai Chernykh at the Crimean Astrophysical Observatory in Nauchnyj. 
 Question: Who discovered 1836 Komarov?

Output: nikolai chernykh


Input: Consider Input: Context: Brink (Sir Cedric Hardwicke) has recently taken Pud's (Bobs Watson) parents in an auto wreck. Brink later comes for Gramps (Lionel Barrymore). Believing Brink to be an ordinary stranger, the crotchety old Gramps orders Mr. Brink off the property. Pud comes out of the house and asks who the stranger was. Gramps is surprised and relieved that someone else could see the stranger; he was not merely a dream or apparition. Pud tells Gramps that when he does a good deed, he will be able to make a wish. Because his apples are constantly being stolen, Gramps wishes that anyone who climbs up his apple tree will have to stay there until he permits them to climb down. Pud inadvertently tests the wish when he has trouble coming down from the tree himself, becoming free only when Gramps says he can. Pud's busybody Aunt Demetria (Eily Malyon) has designs on Pud and the money left him by his parents. Gramps spends much time fending off her efforts to adopt the boy. Brink takes Granny Nellie (Beulah Bondi) in a peaceful death just after she finishes a bit of knitting. When Mr. Brink returns again for Gramps, the old man finally realizes who his visitor is. Determined not to leave Pud to Demetria, Gramps tricks Mr. Brink into climbing the apple tree. While stuck in the tree, he cannot take Gramps or anyone else. The only way anyone or anything can die is if they touch Mr. Brink or the apple tree. Demetria plots to have Gramps committed to a psychiatric hospital when he claims that Death is trapped in his apple tree. Gramps proves his story first by proving that his doctor, Dr. Evans (Henry Travers), can not even kill a fly they have captured. He offers further proof of his power by shooting Mr. Grimes (Nat Pendleton), the orderly who has come to take him to the asylum; Grimes lives when he should have died. Dr. Evans is now a believer, but he tries to convince Gramps to let Death down so people who are suffering can find release. Gramps refuses, so the doctor arranges for the local sheriff to commit Gramps while Pud is delivered to Demetria's custody. With the help of his housekeeper (Una Merkel), Gramps tricks both of them into believing they are scheduled to go with Mr. Brink when he comes down from the tree. They beg Gramps to convince Brink otherwise, and Demetria vows never to bother Gramps or Pud again. Gramps realizes that sooner or later he will have to let Brinks downDeath is an ultimately unavoidable part of life. He tries to say goodbye to Pud, who reacts angrily and tries to run away. Mr. Brink sees Pud in the yard and dares him to climb the tree. Pud gets over the fence Gramps has had built around the tree, but falls and is crippled for life. Distraught, Gramps lets Death down from the tree. He takes both Gramps and Pud, who find they can walk again. In the final scene, they walk together up a beautiful country lane and hear Granny Nellie calling to them from beyond a brilliant light. 
 Question: What does Gramps trick Mr. Brink into doing?

Output: climbing the apple tree


Input: Consider Input: Context: Fossil fuels are made from plants and animals that lived hundreds of millions of years ago. The plants and animals died. Their remains settled onto the ground and at the bottom of the sea. Layer upon layer of organic material was laid down. Eventually, the layers were buried very deeply. They experienced intense heat and pressure. Over millions of years, the organic material turned into fossil fuels. Fossil fuels are compounds of carbon and hydrogen, called hydrocarbons. Hydrocarbons can be solid, liquid, or gas. The solid form is coal. The liquid form is petroleum, or crude oil. The gaseous form is natural gas. Coal is a solid hydrocarbon. Coal is useful as a fuel, especially for generating electricity. Coal forms from dead plants that settled at the bottom of swamps millions of years ago. Water and mud in the swamp kept oxygen away from the plant material. Sand and clay settled on top of the decaying plants. The weight of this material squeezed out the water and some other substances. Over time, the organic material became a carbon-rich rock. This rock is coal. Coal is a black or brownish-black rock that burns easily (Figure 5.3). Most coal is sedimentary rock. The hardest type of coal, anthracite, is a metamorphic rock. That is because it is exposed to higher temperature and pressure as it forms. Coal is mostly carbon, but some other elements can be found in coal, including sulfur. Around the world, coal is the largest source of energy for electricity. The United States is rich in coal. Pennsylvania and the region to the west of the Appalachian Mountains are some of the most coal-rich areas of the United States. Coal has to be mined to get it out of the ground. Coal mining affects the environment and human health. Coal mining can take place underground or at the surface. Each method has some advantages and disadvantages. Surface mining exposes minerals that were underground to air and water at the surface. These minerals contain the chemical element sulfur. Sulfur mixes with air and water to make sulfuric acid. This acid is a highly corrosive chemical. Sulfuric acid gets into nearby streams and can kill fish, plants, and animals. Surface mining is safer for the miners. Coal mining underground is dangerous for the coal miners. Miners are sometimes killed if there is an explosion or a mine collapse. Miners breathe in coal dust and can get terrible lung diseases after a number of years in the mines. To prepare coal for use, the coal is first crushed into powder and burned in a furnace. Like other fuels, coal releases most of its energy as heat when it burns. The heat from the burning coal is used to boil water. This makes steam. The steam spins turbines, which creates electricity. Oil is a thick, dark brown or black liquid. It is found in rock layers of the Earths crust. Oil is currently the most commonly used source of energy in the world. The way oil forms is similar in many ways to coal. Tiny organisms like plankton and algae die and settle to the bottom of the sea. Sediments settle over the organic material. Oxygen is kept away by the sediments. When the material is buried deep enough, it is exposed to high heat and pressure. Over millions of years, the organic material transforms into liquid oil. The United States produces only about one-quarter as much oil as it uses. The main oil producing regions in the U.S. are the Gulf of Mexico, Texas, Alaska, and California. Geologists look for oil in folded layers of rock called anticlines. Oil moves through permeable rock and is trapped by the impermeable cap rock. Oil comes out of the ground as crude oil. Crude oil is a mixture of many different hydrocarbons. Oil is separated into different compounds at an oil refinery (Figure 5.4). This is done by heating the oil. Each hydrocarbon compound in crude oil boils at a different temperature. We get gasoline, diesel, and heating oil, plus waxes, plastics, and fertilizers from crude oil. These fuels are 
 Question: fossil fuel that produces the least pollution when burned


Output: natural gas