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: Hepatitis B is a disease of the liver. It is caused by a virus called hepatitis B, which can be passed through sexual activity. Hepatitis B causes vomiting. It also causes yellowing of the skin and eyes. The disease goes away on its own in some people. Other people are sick for the rest of their lives. In these people, the virus usually damages the liver. It may also lead to liver cancer. Medicines can help prevent liver damage in these people. There is also a vaccine to protect against hepatitis B. 
Story: Ben and Sam were two twin brothers. One day Ben was feeling sick so they went to the doctor and they discovered that Ben had hepatitis B. Sam was tested as well, but he was  'healthy as an ox'. 
Question: Which brother experienced more yellowing of the eyes?
answer:
Ben.


question:
Background Paragraph: Mechanical weathering increases the rate of chemical weathering. As rock breaks into smaller pieces, the surface area of the pieces increases. With more surfaces exposed, there are more places for chemical weathering to occur ( Figure below ). Let’s say you wanted to make some hot chocolate on a cold day. It would be hard to get a big chunk of chocolate to dissolve in your milk or hot water. Maybe you could make hot chocolate from some smaller pieces like chocolate chips, but it is much easier to add a powder to your milk. This is because the smaller the pieces are, the more surface area they have. Smaller pieces dissolve more easily. 
Story: Rocks commonly found in Beijing are often found spread out in smaller pieces, whereas rocks in Montreal typically remain large in size and don't break apart as much. Both Beijing and Montreal are expected to experience bouts of acid rain in the upcoming weeks. 
Question: Which area's rocks will have higher rates of chemical weathering caused by the acid rain?
answer:
Beijing.


question:
Background Paragraph: Some Chinese martial arts instructors focus more on their qinna techniques than others. This is one of the many reasons why the qinna of one school may differ from that of another.[2] All martial arts contain qinna techniques in some degree. The southern Chinese martial arts have more developed qinna techniques than northern Chinese martial systems. The southern martial arts have much more prevalent reliance on hand techniques which causes the practitioner to be in closer range to their opponent. There are over 700 qinna traditional techniques found in all martial arts. In the Non-Temple White Crane style there are 150-200 qinna techniques alone. Along with Fujian White Crane, styles such as Northern Eagle Claw (Ying Jow Pai) and Tiger Claw (Fu Jow Pai) have qinna as their martial focus and tend to rely on these advanced techniques. 
Story: There is a long history of martial arts competition in Fujian Province of China. Interestingly, one can also place bets on competitors. David is a martial arts enthusiast, watching every martial arts movie he can find. This year David and his friend John is visiting the Fujian Province to see the martial arts competition. There are two rounds of competition, round A and round B. Round A competitors would display southern Chinese martial arts while round B competitors would display northern Chinese martial arts. 
Question: If David bets on seeing more hand techniques, which round would he pick?
answer:

round A.