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: The example of someone having a positive experience with a drug is easy to see how drug dependence and the law of effect works. The tolerance for a drug goes up as one continues to use it after having a positive experience with a certain amount the first time.[38] It will take more and more to get that same feeling. This is when the controlled substance in an experiment would have to be modified and the experiment would really begin. The law of work for psychologist B. F. Skinner almost half a century later on the principles of operant conditioning, "a learning process by which the effect, or consequence, of a response influences the future rate of production of that response.[39].
Story: The Boat Ballers met to discuss their experiences. They all said they always had a great experience using boat and used the same amount each time. They told how many times they used boat. Les used it 99 times, Osvaldo used it 89 times, Dino used it 79 times, Refugio used it 69 times, Coleman used it 59 times, Margarito used it 49 times, and Alden used it 39 times.
Question: Who has a higher tolerance for boat: Refugio or Les?

Answer: Les.

Question: Background Paragraph: Common causes of heat exhaustion include:[1]

Hot, sunny, humid weather
Physical exertion, especially in hot, humid weather
Due to impaired thermoregulation, elderly people and infants can get serious heat illness even at rest, if the weather outside is hot and humid, and they are not getting enough cool air.
Some drugs, such as diuretics, antihistamines, beta-blockers, alcohol, ecstasy, and amphetamines can cause an increase in the risk of heat exhaustion.[2]
Especially during physical exertion, risk factors for heat exhaustion include:[1]

Wearing dark, padded, or insulated clothing; hats; and/or helmets (for example, football pads or turnout gear)
Having a higher percentage of body fat
Dehydration
Fever
Some medications, like beta blockers and antipsychotic medicines[2].
Story: Two groups of people were out in the sunny, humid weather of Illinois. Group One wore black clothes and helmets, and Group Two wore white, light clothing. Both groups were comprised of people of all ages and fitness levels and exercised in the sun for an hour.
Question: Which group had more inebriated people experiencing heat illness?

Answer: Group One.

Question: Background Paragraph: Sand mining is a direct cause of erosion, and impacts the local wildlife.[2] Various animals depend on sandy beaches for nesting clutches, and mining has led to the near extinction of gharials (a species of crocodile) in India. Disturbance of underwater and coastal sand causes turbidity in the water, which is harmful for organisms like coral that need sunlight. It can also destroy fisheries, financially harming their operators.

Removal of physical coastal barriers, such as dunes, sometimes leads to flooding of beachside communities, and the destruction of picturesque beaches causes tourism to dissipate. Sand mining is regulated by law in many places, but is often done illegally.[3] Globally, it is a $70 billion industry, with sand selling at up to $90 per cubic yard.[4].
Story: Sand mining in the north coastal region was stopped 20 years ago, but it still continues to this day in the south region. Both fishing communities there are still prosperous, but the southern one had a couple of bad years, with fish and other marine wildlife becoming more scarce. The southern beach had erosion problems as well. The northern beach recovered, and is suitable for tourism.
Question: Which region has a lower water turbidity?

Answer:
northern.