TASK DEFINITION: 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.
PROBLEM: Background Paragraph: If a solution has a higher concentration of hydronium ions than pure water, it has a pH lower than 7. A solution with a pH lower than 7 is called an acid . As the hydronium ion concentration increases, the pH value decreases. Therefore, the more acidic a solution is, the lower its pH value is. Did you ever taste vinegar? Like other acids, it tastes sour. Stronger acids can be harmful to organisms. For example, stomach acid would eat through the stomach if it were not lined with a layer of mucus. Strong acids can also damage materials, even hard materials such as glass. 
Story: In his chemistry lab David is learning about acids. He took three solutions to identify them correctly, sample A, sample B, and sample C. Sample A is a strong acid; sample B is a weak acid; and sample C is not an acid. David needs to identify the content of each sample by learning about their attributes. 
Question: Which sample would most likely damage materials, sample A or sample B?

SOLUTION: sample A.

PROBLEM: Background Paragraph: Groundwater salinization compromises buffering properties. Vegetation clearance, along with irrigation, causes serious issues. Irrigation increases the water table and mobilizes salts, and vegetation clearance allows it to come in contact with water habitats and vegetation. This stresses species not adapted to high salinity. High levels of salinity reduces water uptake in plants, by causing stomatal closure, reducing photosynthesis. Forests undergo decline in areas of high salinity and shallow groundwater depths because these conditions make them more susceptible to droughts. Forests undergo decline in areas of high salinity and shallow groundwater depths making them more susceptible to droughts. 
Story: Roger has been wanting to make a difference in the world, and has decided he wants to start a forested area in the country side. He has some areas that he has mapped out, and is trying to decide where he would like to start his new growth. The Bilton Valley area has recently been cleared of vegetation and has some irrigation channels installed for a near by farm. The other area he is looking at in an uncleared pasture called Stevens Pasture. 
Question: Will Stevens Pasture have a more reduced or increased water uptake by plants than Bilton Valley?

SOLUTION: increased.

PROBLEM: Background Paragraph: In many ways, bacterial metabolism provides traits that are useful for ecological stability and for human society. One example is that some bacteria have the ability to fix nitrogen gas using the enzyme nitrogenase. This environmentally important trait can be found in bacteria of most metabolic types listed above. This leads to the ecologically important processes of denitrification, sulfate reduction, and acetogenesis, respectively. Bacterial metabolic processes are also important in biological responses to pollution; for example, sulfate-reducing bacteria are largely responsible for the production of the highly toxic forms of mercury (methyl- and dimethylmercury) in the environment. Non-respiratory anaerobes use fermentation to generate energy and reducing power, secreting metabolic by-products (such as ethanol in brewing) as waste. Facultative anaerobes can switch between fermentation and different terminal electron acceptors depending on the environmental conditions in which they find themselves. 
Story: Brett and Scott were both studying bacteria for their exam. Scott read more about nitrogen-fixating and sulfate-reducing bacteria, while his colleague Brett read more about non-respiratory anaerobe bacteria and facultative anaerobes. 
Question: Which student read more about the production of the highly toxic dimethylmercury?

SOLUTION:
Scott.