You are given a background paragraph that describes one or more causal or qualitative relationships such as a relationship in economics or a scientific law and a story that makes use of the concepts or the relationship described in the provided paragraph. You are also given a question about the story that requires an understanding of the relationship described in the background paragraph and the story. You need to come up with an answer to the given question; the answer will be a span from either the question or the story. In order to correctly answer the given question, you need to understand the relationship mentioned in the background paragraph and should be able to use it to understand that in the story. Your answer can not consist of any word that is not mentioned in any of these: the background paragraph, the story, or the question. You can directly copy and paste a span from the story or the question while answering the given question.

Q: Background Paragraph: There is growing concern regarding the use of pesticides in agriculture. Therefore, many of the current commercial applications of modern biotechnology in agriculture are focused on reducing the dependence of farmers on these chemicals. For example, Bacillus thuringiensis (Bt) is a soil bacterium that produces a protein that can act as an insecticide, known as the Bt toxin . But it is a naturally occurring protein, not a foreign chemical. Could this protein be used in crops instead of pesticides? Traditionally, an insecticidal spray has been produced from these bacteria. As a spray, the Bt toxin is in an inactive state and requires digestion by an insect to become active and have any effect. Crop plants have now been engineered to contain and express the genes for the Bt toxin, which they produce in its active form. When an insect ingests the transgenic crop, it stops feeding and soon thereafter dies as a result of the Bt toxin binding to its gut wall. Bt corn is now commercially available in a number of countries to control corn borer (an insect like a moth or butterfly), which is otherwise controlled by insecticidal spraying. 
Story: Environmental scientists are trying to find a solution to reducing the harmful effects of chemicals on the environment. To that end, they developed a transgenic crop with the help of Bt toxin - they referred to it as case A. To test the effectiveness of this new crop they also studied Bt toxin spray - they referred to it as case B. They need to figure out which case is safer for the environment. 
Question: In which case the Bt toxin would not bind to the insect's gut wall, case A or case B?

A: case B.
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Q: Background Paragraph: Huge amounts of chemicals, such as fertilizers and pesticides, are applied to farm fields (see Figure below ). Some of the chemicals are picked up by rainwater. Runoff then carries the chemicals to nearby rivers or lakes. Dissolved fertilizer causes too much growth of water plants and algae. This can lead to dead zones where nothing can live in lakes and at the mouths of rivers. Some of the chemicals can infiltrate into groundwater. The contaminated water comes up in water wells. If people drink the polluted water, they may get sick. 
Story: Lucy and Sarah are two people who each own a lake that they enjoy spending time at. They have to take care of the lake though and make sure everything is healthy so that the lake can continue to thrive and people will want to visit it. Sarah says she heard a secret that if you dump fertilizer into your lake, the fish will grow twice as large. Sarah says she has just started doing it this past week and can't wait to see the results. Lucy is skeptical and waits to see what happens at Sarah's lake. 
Question: Will Lucy or Sarah have a lake with less plants in it?

A: Lucy.
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Q: Background Paragraph: One of the main causes of extinction is introduction of exotic species into an environment. These exotic and new species can also be called invasive species or non-native species . These non-native species, being new to an area, may not have natural predators in the new habitat, which allows their populations to easily adapt and grow. Invasive species out-compete the native species for resources. Sometimes invasive species are so successful at living in a certain habitat that the native species go extinct ( Figure below ). 
Story: India decided to introduce several exotic species into their environment, while Singapore was very protective of its native species. 
Question: Which country introduced more non-native species to the environment?

A:
India.
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