[Q]: I read this background article the other day: A major use for petroleum products is fuel for cars, trucks, airplanes, trains, and other vehicles. The chemical used are usually a mixture of compounds containing several carbon atoms in a chain. When the material is ignited, a massive amount of gas is created almost instantaneously. This increase in volume will move the pistons in an internal combustion engine to provide power. A jet plane works on a similar principle. Air comes into the front of the engine and mixes with the jet fuel. This mixture is ignited and the gases formed create a lot of pressure to push the plane forward. The idea can be seen even more clearly in the case of a rocket launch. The ignition of the fuel (either solid-state or liquid) creates gases produced under great pressure that pushes the rocket up. I am facing a new situation today: Two engineering students learned about petroleum products, While Dan learned more about plastics, Jim learned about fuels. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which student learned less about fuels for airplanes?
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[A]: Dan

[Q]: I read this background article the other day: While people have been able to prevent certain viral diseases by vaccinations for many hundreds of years, the development of antiviral drugs to treat viral diseases is a relatively recent development. Antiviral drugs are medications used specifically for treating the symptoms of viral infections. The first antiviral drug was interferon , a substance that is naturally produced by certain immune cells when an infection is detected. Over the past twenty years the development of antiretroviral drugs (also known as antiretroviral therapy, or ART) has increased rapidly. This has been driven by the AIDS epidemic. I am facing a new situation today: Bob was a medical student and he studied drugs administered to people with viral diseases, while his colleague Liam decided to study other types of drugs, such as antibiotics and anticoagulants. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which colleague studied more about the development of antiretroviral drugs?
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[A]: Bob

[Q]: I read this background article the other day: The benefits provided by no-tillage to predators may lead to larger predator populations, which is a good way to control pests (biological control), but also can facilitate predation of the crop itself. In corn crops, for instance, predation by caterpillars can be higher in no-till than in conventional tillage fields.In places with rigorous winter, untilled soil can take longer to warm and dry in spring, which may delay planting to less ideal dates. Another factor to be considered is that organic residue from the prior year's crops lying on the surface of untilled fields can provide a favorable environment to pathogens, helping to increase the risk of transmitting diseases to the future crop. And because no-till farming provides good environment for pathogens, insects and weeds, it can lead farmers to a more intensive use of chemicals for pest control. Other disadvantages of no-till include underground rot, low soil temperatures and high moisture.Based on the balance of these factors, and because each farm has different problems, agroecologists will not attest that only no-till or complete tillage is the right way of farming. Yet, these are not the only possible choices regarding soil preparation, since there are intermediate practices such as strip-till, mulch-till and ridge-till, all of them just as no-till categorized as conservation tillage. Agroecologists, then, will evaluate the need of different practices for the contexts in which each farm is inserted. I am facing a new situation today: Barb and Jill practiced small scale farming. Jill farmed the conventional way, while barb used the no-tillage method. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which farmer had soil that took longer to warm in spring?
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[A]: Barb

[Q]: I read this background article the other day: Sand mining is a direct cause of erosion, and impacts the local wildlife.[2] Various animals depend on sandy beaches for nesting clutches, and mining has led to the near extinction of gharials (a species of crocodile) in India. Disturbance of underwater and coastal sand causes turbidity in the water, which is harmful for organisms like coral that need sunlight. It can also destroy fisheries, financially harming their operators. Removal of physical coastal barriers, such as dunes, sometimes leads to flooding of beachside communities, and the destruction of picturesque beaches causes tourism to dissipate. Sand mining is regulated by law in many places, but is often done illegally.[3] Globally, it is a $70 billion industry, with sand selling at up to $90 per cubic yard.[4] I am facing a new situation today: Nigeria invested in sand mining and started mining coastal barriers. Congo continued preserving their picturesque beaches. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which country destroyed fewer of their beaches?
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[A]:
Congo