[Q]: I read this background article the other day: Cholesterol can't dissolve in the blood. It has to be transported to and from the cells by carriers called lipoproteins. Low-density lipoprotein, or LDL, is known as "bad" cholesterol. High-density lipoprotein (HDL) is known as good cholesterol. When too much LDL cholesterol circulates in the blood, it can slowly build up in the inner walls of the arteries that feed the heart and brain. Together with other substances, it can form plaque, and lead to atherosclerosis. If a clot forms and blocks a narrowed artery, a heart attack or stroke can result. Cholesterol comes from the food you eat as well as being made by the body. To lower bad cholesterol, a diet low in saturated fat and dietary cholesterol should be followed. Regular aerobic exercise also lowers LDL cholesterol and increases HDL cholesterol. I am facing a new situation today: John is a doctor with the local hospital. Earlier today, he was seeing two patients, patient A and patient B. John found out that patient A had more LDL, but patient B had more HDL. He now needs to determine correct treatment for them. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which patient would have lower risk of atherosclerosis, patient A or patient B?
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[A]: patient B

[Q]: I read this background article the other day: One reason radiation is dangerous is that it can't be detected with the senses. You normally can't see it, smell it, hear it, or feel it. Fortunately, there are devices such as Geiger counters that can detect radiation. A Geiger counter, like the one in Figure below , has a tube that contains atoms of a gas. If radiation enters the tube, it turns gas atoms to ions that carry electric current. The current causes the Geiger counter to click. The faster the clicks occur, the higher the level of radiation. I am facing a new situation today: David was visiting Japan. First, he went to Fukushima where the recent nuclear plant disaster happened. He found the city still had very high radiation. Then he visited Hiroshima. He found that Hiroshima had some low radiation. Finally, he visited the capital city Tokyo. He found that Tokyo did not have any radiation. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: In which city the gas inside a Geiger counter would not be ionized, Hiroshima or Tokyo?
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[A]: Tokyo

[Q]: I read this background article the other day: A vapor light also produces visible light by electroluminescence The bulb contains a small amount of solid sodium or mercury as well as a mixture of neon and argon gases. When an electric current passes through the gases, it causes the solid sodium or mercury to change to a gas and emit visible light. Sodium vapor lights, like the streetlight pictured in the Figure below , produce yellowish light. Mercury vapor lights produce bluish light. In addition to lighting city streets, vapor lights are used to light highways and stadiums. The bulbs are very bright and long lasting so they are a good choice for these places. I am facing a new situation today: Joe walks into his house to see that his son has replaced the light bulbs in both the kitchen and the bathroom. The kitchen is now glowing blue because of the light bulb, and the bathroom has a yellow tint to it. Joe decides he needs to find his son to figure out what type of light bulbs these are and why he chose them. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which room has a light bulb filled with sodium vapor?
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[A]: bathroom

[Q]: I read this background article the other day: Electromagnetic radiation is energy that travels in waves across space as well as through matter. Most of the electromagnetic radiation on Earth comes from the sun. Like other waves, electromagnetic waves are characterized by certain wavelengths and wave frequencies. Wavelength is the distance between two corresponding points on adjacent waves. Wave frequency is the number of waves that pass a fixed point in a given amount of time. Electromagnetic waves with shorter wavelengths have higher frequencies and more energy. I am facing a new situation today: David is experimenting with electromagnetic waves. He has four different waves to study, wave A, wave B, wave C, and wave D. In wave A, distance between two corresponding points on adjacent waves is greater than that of wave B. In wave C, the number of waves that pass a fixed point in a given time is greater than that of wave D. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which wave has lower frequency, wave A or wave B?
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[A]:
wave A