instruction:
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: A large log placed in a fire will burn relatively slowly. If the same mass of wood were added to the fire in the form of small twigs, they would burn much more quickly. This is because the twigs provide a greater surface area than the log does. An increase in the surface area of a reactant increases the rate of a reaction. Surface area is larger when a given amount of a solid is present as smaller particles. A powdered reactant has a greater surface area than the same reactant as a solid chunk. In order to increase the surface area of a substance, it may be ground into smaller particles or dissolved into a liquid. In solution, the dissolved particles are separated from each other and will react more quickly with other reactants. 
Story: Two groups of friends went camping , but camped separately a few hundred yards away and started a fire each. Both groups had the same volume of wood. Group P had larger logs, while group Q had small twigs, sawdust and kindlings. 
Question: Which group didn't bring small particles of wood to burn?
answer:
Group P.


question:
Background Paragraph: You may hear males "ribbiting," producing a mating call used to attract females to the bodies of water best for mating and breeding. Frog calls can occur during the day or night. Each frog species has a different call that is used to attract mates and warn off rivals. When a female picks a male whose call she likes, the male grabs her and squeezes across her back and around her abdomen. This causes the female to release her eggs. The male then fertilizes the eggs and, in some species, also guards them. 
Story: Sandra liked all creatures but loved to study frogs. Her sister Julie studied more about fish and butterflies. They both loved nature. 
Question: Which sister learned more about different calls used by different species of frogs?
answer:
Sandra.


question:
Background Paragraph: Of the 94 naturally occurring elements, those with atomic numbers 1 through 82 each have at least one stable isotope (except for technetium, element 43 and promethium, element 61, which have no stable isotopes). Isotopes considered stable are those for which no radioactive decay has yet been observed. Elements with atomic numbers 83 through 94 are unstable to the point that radioactive decay of all isotopes can be detected. Some of these elements, notably bismuth (atomic number 83), thorium (atomic number 90), and uranium (atomic number 92), have one or more isotopes with half-lives long enough to survive as remnants of the explosive stellar nucleosynthesis that produced the heavy metals before the formation of our Solar System. At over 1.9×1019 years, over a billion times longer than the current estimated age of the universe, bismuth-209 (atomic number 83) has the longest known alpha decay half-life of any naturally occurring element, and is almost always considered on par with the 80 stable elements. The very heaviest elements (those beyond plutonium, element 94) undergo radioactive decay with half-lives so short that they are not found in nature and must be synthesized. 
Story: David was studying for his chemistry exam. To understand the elements of the periodic table better he categorized them into three groups, cat A, cat B, and cat C. In cat A he placed all the elements with atomic numbers lower than 83. In cat B he put the elements with atomic numbers from 83 to 94. Finally, in cat C he placed the elements with atomic numbers over 94. He found it easier to see their differences after he categorized them. 
Question: Which category would more likely have stable isotopes, cat A or cat B?
answer:

cat A.