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.
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Question: Background Paragraph: Chemical reactions follow the laws of thermodynamics. The First Law of Thermodynamics states that energy can be changed from one form to another, but it cannot be created or destroyed. This law is also known as the Law of Conservation of Energy. The Second Law of Thermodynamics states the energy available after a chemical reaction is always less than that at the beginning of a reaction. This is also commonly referred to as entropy. Entropy can be described as the degree of disorder in a system . That is, as energy is transferred from one form to another, some of the energy is lost as heat, and the amount of available energy decreases. As the energy decreases, the disorder in the system increases, and, by definition, the entropy increases. Ice melting provides an example in which entropy increases. Entropy essentially is a measure of the tendency of a process, such as a chemical reaction, to proceed in a particular direction. 
Story: Marcus is in a lab working on an experiment. He combines two chemicals to see if they react and the solution starts to boil. He notices that the air above the chemicals reacting has greatly increased in heat. 
Question: Will the disorder of a system increase or decrease as entropy increases?

Answer: increase.


Question: Background Paragraph: The epidermis also contains melanocytes , which are cells that produce melanin. Melanin is the brownish pigment that gives skin much of its color. Everyone has about the same number of melanocytes, but the melanocytes of people with darker skin produce more melanin. The amount of melanin produced is determined by heredity and exposure to UV light, which increases melanin output. Exposure to UV light also stimulates the skin to produce vitamin D . Because melanin blocks UV light from penetrating the skin, people with darker skin may be at greater risk of vitamin D deficiency. 
Story: Matt and his brother Jesse are twins. They look almost identical. If it weren't for the fact that Jesse has a slightly darker skin complexion you wouldn't be able to tell them apart. In fact one year Matt was out in the sun for a long time and picked up a bit of a tan so they actually did look exactly alike. 
Question: Will an increase in the amount of melanin produced make a person skin darker or lighter?

Answer: darker.


Question: Background Paragraph: The epidermis also contains melanocytes , which are cells that produce melanin. Melanin is the brownish pigment that gives skin much of its color. Everyone has about the same number of melanocytes, but the melanocytes of people with darker skin produce more melanin. The amount of melanin produced is determined by heredity and exposure to UV light, which increases melanin output. Exposure to UV light also stimulates the skin to produce vitamin D . Because melanin blocks UV light from penetrating the skin, people with darker skin may be at greater risk of vitamin D deficiency. 
Story: An anthropologist gathered observations for two native tribes from southern Africa.  He noticed that both tribes spend the majority of the day outside, and therefore they are both exposed to fairly high amounts of UV light. He also quickly realized that one key difference between the tribes was that members of tribe A had dark skin, while members of tribe B had light skin. 
Question: Members of which tribe will produce less melanin?

Answer:
tribe B.