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.
--------
Question: Background Paragraph: Besides anthropogenic productivity of the land, the biodiversity of degraded land also declines, as previously mentioned.[12] With less biodiversity, this ecosystem is less adaptable to when disasters strike it[11][8] It has a smaller available food supply, in terms of plants, for animals, who then may die out or more likely may relocate. Proof of this decline is that presently 15-20% of Tibetan Plateau species are now considered endangered; and now because of this animal and plant absence, the soil quality of these degraded lands is very poor.[1] It does not hold the necessary nutrients, such as water, nitrogen, and carbon, essential to either supporting life or inviting life back to that land.[6] As a result of such carbon and nitrogen loss in the Tibetan Plateau, $8,033/ha and $13,315/ha were respectively lost in economic terms. Soils are further weakened by dust storms whose frequency increases because of degradation.[11][4] Erosion of soil becomes a bigger problem, since no longer are there as many plants to anchor in the soil. In the northern Chinese province alone, 400 million are affected every year with an associated 54 billion yuan of annual economic loss due to grassland degradation. 
Story: Xi province started sustainable agriculture and permaculture 40 years ago, while Huan province still uses conventional methods of cultivation.  Animals grazing the fields extensively lead to desertification, the loss of carbon and nitrogen in the soil, and other problems. Permaculture was beneficial in Xi province, they re-built 10 inches of top soil in 10 years which is 6 times faster than the natural rate, which lead to a more diverse ecosystem and more biodiversity. 
Question: Which province contributed to soil degradation less?

Answer: Xi province.


Question: Background Paragraph: Before iodized salt was developed, some people experienced a number of developmental difficulties, including problems with thyroid gland function and mental retardation. In the 1920s, we learned that these conditions could usually be treated easily with the addition of iodide anion to the diet. One easy way to increase iodide intake was to add the anion to table salt. This simple step greatly enhanced health and development. Large amounts of iodide ion are also found in seaweed such as kelp (see picture above) and saltwater fish. 
Story: People from two villages ate lots of salt. People from Salt village used regular salt, while people from Sand village people used iodized salt in their diets, after talking to specialists. 
Question: Which village had fewer people experience developmental difficulties?

Answer: Sand.


Question: Background Paragraph: Pressures are given in a multitude of units. We've already discussed Pascals, and we know that another unit for pressure is the atmosphere (1 atm = 101.3 x 10 5 Pa). The third commonly used pressure unit is the torr (symbol Torr). 760 torr is 1 atm, but 1 torr is also the increase in pressure necessary to cause liquid mercury to rise by 1 mm. For that reason, torr is also commonly referred to as "millimeters mercury." Another pressure unit commonly used in our everyday world is psi, or pounds per square inch, though neither psi nor torr are SI units. 
Story: Mike is studying for his physics exam. He realizes that the best way to learn physics is to solve problems. To that end, he needs to to convert pressure of objects from one unit to another. In one problem, four scenarios are given for the same object, scenario A, scenario B, scenario C, and scenario D. In scenario A the pressure is given in Pascals. In scenario B the pressure is given in the atm. In scenario C the pressure is given in torr. Lastly, in scenario D the pressure is given in psi. 
Question: In which scenario mercury may not be a factor in devising the unit, scenario A or scenario C?

Answer:
scenario A.