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: In grassland, much of the organic matter added to the soil is from the deep, fibrous, grass root systems. By contrast, tree leaves falling on the forest floor are the principal source of soil organic matter in the forest. Another difference is the frequent occurrence in the grasslands of fires that destroy large amounts of aboveground material but stimulate even greater contributions from roots. Also, the much greater acidity under any forests inhibits the action of certain soil organisms that otherwise would mix much of the surface litter into the mineral soil. As a result, the soils under grasslands generally develop a thicker A horizon with a deeper distribution of organic matter than in comparable soils under forests, which characteristically store most of their organic matter in the forest floor (O horizon) and thin A horizon. 
Story: In the Kenya-Tanzania border Kenyan grassland gradually merges into Tanzanian forest. Though they had similar soil to start with millions of years ago, today they are two different habitats. At present, Kenya has one of the largest contiguous grassland in Africa. On the other hand, Tanzania boasts one of the largest forest cover in Africa. 
Question: Which place would have thinner "A horizon", Kenya or Tanzania?
[A]: Tanzania.


[Q]: Background Paragraph: Many different chemical substances cause cancer. Dozens of chemicals in tobacco smoke, including nicotine, have been shown to cause cancer ( Figure below ). In fact, tobacco smoke is one of the main sources of chemical carcinogens. Smoking tobacco increases the risk of cancer of the lung, mouth, throat, and bladder. Using smokeless tobacco can also cause cancer. Other chemicals that cause cancer include asbestos, formaldehyde, benzene, cadmium, and nickel. 
Story: Two ladies sit in a coffee shop. Patty smokes three packs of cigarettes a day, but her good friend Julie, doesn't smoke. They are both 65 years old. They are enjoying a coffee. 
Question: Which lady is less exposed chemical carcinogens?
[A]: Julie.


[Q]: Background Paragraph: Mass is a measure of the amount of matter in a substance or an object. The basic SI unit for mass is the kilogram (kg), but smaller masses may be measured in grams (g). To measure mass, you would use a balance. In the lab, mass may be measured with a triple beam balance or an electronic balance, but the old-fashioned balance pictured below may give you a better idea of what mass is. If both sides of this balance were at the same level, it would mean that the fruit in the left pan has the same mass as the iron object in the right pan. In that case, the fruit would have a mass of 1 kg, the same as the iron. As you can see, however, the fruit is at a higher level than the iron. This means that the fruit has less mass than the iron, that is, the fruit's mass is less than 1 kg. 
Story: Johnathan is trying to find two blocks of wood with the same mass for a project he is working on. He doesn't have a balance, so he makes a crude one out of materials he has on hand. He put a block of wood on either side and the block on the left side was at a lower level than the block on the right. 
Question: Does the block of wood on the right side have more or less mass than the block of wood on the left side?
[A]:
less.