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.
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Question: Context: An electric transformer is a device that uses electromagnetic induction to change the voltage of electric current. Electromagnetic induction is the process of generating current with a magnetic field. It occurs when a magnetic field and electric conductor, such as a coil of wire, move relative to one another. A transformer may either increase or decrease voltage. You can see the basic components of an electric transformer in the Figure 1.1. Click image to the left or use the URL below. URL: The transformer in the diagram consists of two wire coils wrapped around an iron core. Each coil is part of a different circuit. When alternating current passes through coil P, it magnetizes the iron core. Because the current is alternating, the magnetic field of the iron core keeps reversing. This is where electromagnetic induction comes in. The changing magnetic field induces alternating current in coil S of the other circuit. Notice that coil P and coil S in the Figure 1.1 have the same number of turns of wire. In this case, the voltages of the primary and secondary currents are the same. Usually, the two coils of a transformer have different numbers of turns. In that case, the voltages of the two currents are different. When coil S has more turns than coil P, the voltage in the secondary current is greater than the voltage in the primary current (see Figure 1.2). This type of transformer is called a step-up transformer. Thats because it steps up, or increases, the voltage. When coil S has fewer turns of wire than coil P, the voltage in the secondary current is less than the voltage in the primary current (see Figure 1.3). This type of transformer is called a step-down transformer because it steps down, or decreases, the voltage. Q: Both step-up and step-down transformers are used in the electrical grid that carries electricity from a power plant to your home. Where in the grid do you think step-down transformers might be used? A: One place that step-down transformers are used is on the electric poles that supply current to homes. They reduce the voltage of the electric current before it enters home circuits. 
 Question: an electric transformer contains

Answer: an iron core.


Question: Context: The film explores adolescent issues through the minds of three friends and their reactions after a boy named Rudy Carges (Conor Donovan) is killed in a tree house set on fire by local bullies Jeff and Kenny, who carelessly didn't find out he was inside until too late. The boy's twin brother Jacob, a boy with a huge birthmark (also played by Donovan), decides to seek revenge against the bullies. Leonard (Jesse Camacho) who's overweight, survives the tree house fire but loses his sense of taste and smell. Thanks to the fire, this prompts Leonard to go on a diet, which isn't welcomed by his obese family. The boys' female friend Malee (Zoe Weizenbaum) tries to befriend an adult named Gus (Jeremy Renner), a grief-stricken patient of her therapist mother, Carla (Annabella Sciorra). Jacob's family falls apart after the death of his brother. But shortly after, his parents adopt a boy named Keith Gardner. Meanwhile, Malee begins to have a crush on Gus and changes the song for her recital to one Gus liked, just for him. As time goes by, she sees Gus as her "soul mate". She sneaks into his house one night to find him grieving. Afraid to confront him, Malee steals his gun and leaves. She gives it to Jacob the following day. Jacob frequently visits Jeff and Kenny, who are serving time in a juvenile hall. Jacob initially threatens them, until eventually Jeff commits suicide. Jacob befriends Kenny, soon learning he has an early release and is illegally moving to New Mexico. Meanwhile, Leonard's father decides to take his sisters to Florida instead of Leonard (who would usually go). Leonard decides to force his mother to lose weight by trapping her in the cellar. They both end up in the hospital after a gas leak in their home. Next, Jacob and Kenny agree that Jacob can go with him to New Mexico. Malee visits Gus and removes her clothes in an attempt to seduce him. Instead, Gus calls Malee's mother to come and pick her up. The next day, Gus explains to therapist Carla about the last fire he ever fought (which involved killing an injured little girl, upon the girl's request), claiming that Malee wanted him to take her pain away, as he was aware of her growing crush on him. Meanwhile, Jacob's mother tells him that Keith Gardner wasn't adopted to replace Rudy, and that she wants Kenny dead, which reminds Jacob of his planned revenge. The night of escape for Jacob finally comes and he meets up with Kenny. Jacob insists on going through a construction site which he says is a secret route. Once there, Jacob points Gus's gun at Kenny, and tells him "you killed him" before shooting him dead. Jacob buries the body and leaves. He returns in the daytime, and sees Gus spreading cement above Kenny's grave. Malee begins visiting her estranged father and Leonard's family finally starts eating healthily. The movie ends with Jacob's mother smiling at him from inside the house. 
 Question: How many stories are there in this film?

Answer: three


Question: Context: Biotic and abiotic factors determine the population size of a species in an ecosystem. What are some important biotic factors? Biotic factors include the amount of food that is available to that species and the number of organisms that also use that food source. What are some important abiotic factors? Space, water, and climate all help determine a species population. When does a population grow? A population grows when the number of births is greater than the number of deaths. When does a population shrink? When deaths exceed births. What causes a population to grow? For a population to grow there must be ample resources and no major problems. What causes a population to shrink? A population can shrink either because of biotic or abiotic limits. An increase in predators, the emergence of a new disease, or the loss of habitat are just three possible problems that will decrease a population. A population may also shrink if it grows too large for the resources required to support it. When the number of births equals the number of deaths, the population is at its carrying capacity for that habitat. In a population at its carrying capacity, there are as many organisms of that species as the habitat can support. The carrying capacity depends on biotic and abiotic factors. If these factors improve, the carrying capacity increases. If the factors become less plentiful, the carrying capacity drops. If resources are being used faster than they are being replenished, then the species has exceeded its carrying capacity. If this occurs, the population will then decrease in size. Every stable population has one or more factors that limit its growth. A limiting factor determines the carrying capacity for a species. A limiting factor can be any biotic or abiotic factor: nutrient, space, and water availability are examples (Figure 1.1). The size of a population is tied to its limiting factor. What happens if a limiting factor increases a lot? Is it still a limiting factor? If a limiting factor increases a lot, another factor will most likely become the new limiting factor. This may be a bit confusing, so lets look at an example of limiting factors. Say you want to make as many chocolate chip cookies as you can with the ingredients you have on hand. It turns out that you have plenty of flour and other ingredients, but only two eggs. You can make only one batch of cookies, because eggs are the limiting factor. But then your neighbor comes over with a dozen eggs. Now you have enough eggs for seven batches of cookies, but only two pounds of butter. You can make four batches of cookies, with butter as the limiting factor. If you get more butter, some other ingredient will be limiting. Species ordinarily produce more offspring than their habitat can support (Figure 1.2). If conditions improve, more young survive and the population grows. If conditions worsen, or if too many young are born, there is competition between individuals. As in any competition, there are some winners and some losers. Those individuals that survive to fill the available spots in the niche are those that are the most fit for their habitat. Click image to the left or use the URL below. URL: A frog in frog spawn. An animal produces many more offspring than will survive. 
 Question: if a pack of coyotes enters a region, the carrying capacity for bunnies will likely

Answer:
decrease.