I read this background article the other day: Active immunity can also result from immunization. Immunization is the deliberate exposure of a person to a pathogen in order to provoke an immune response and the formation of memory cells specific to that pathogen. The pathogen is often injected. However, only part of a pathogen, a weakened form of the pathogen, or a dead pathogen is typically used. This causes an immune response without making the immunized person sick. This is how you most likely became immune to measles, mumps, and chicken pox. You can watch an animation showing how immunization brings about immunity at this link: http://www.biosolutions.info/2009/05/vaccination.html . I am facing a new situation today: When Emily was 4 years old she came down with a case of the chicken pox. She is now 14 and her younger brother Victor has now caught the chicken pox from another child at school. Emily opts to stay home and take care of him. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Will Emily have a high or low chance of catching the chicken pox from her brother?
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Answer: low

I read this background article the other day: Because of human activities, there is more carbon dioxide in the atmosphere today than in the past hundreds of thousands of years. Burning fossil fuels and has released great quantities of carbon dioxide into the atmosphere. Cutting forests and clearing land has also increased carbon dioxide into the atmosphere because these activities reduce the number of autotrophic organisms that use up carbon dioxide in photosynthesis. In addition, clearing often involves burning, which releases carbon dioxide that was previously stored in autotrophs. I am facing a new situation today: When comparing village A from ten thousand years ago to village B from today, we reached the conclusion that today's villagers release much more carbon into the atmosphere by their activities. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which village cleared less land?
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Answer: village A

I read this background article the other day: In the U.S., the majority of electricity is produced by burning coal or other fossil fuels. This causes air pollution, acid rain, and global warming. Fossil fuels are also limited and may eventually run out. Like fossil fuels, radioactive elements are limited. In fact, they are relatively rare, so they could run out sooner rather than later. On the other hand, nuclear fission does not release air pollution or cause the other environmental problems associated with burning fossil fuels. This is the major advantage of using nuclear fission as a source of energy. I am facing a new situation today: Panama and Ecuador are two neighboring countries. Ecuador uses nuclear fusion to produce its electricity, while Panama uses fossil fuels. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which country used fewer radioactive elements?
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Answer:
Panama