Problem: 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. People from two villages got infected with viruses and got sick. People from Hill village got infected with the flu, while people in Valley village got infected with hepatitis B. Which villagers will experience more instances of liver cancer?

A: Valley

Problem: Soil is well developed in the forest as suggested by the thick humus layers, rich diversity of large trees and animals that live there. In forests, precipitation exceeds evapotranspiration which results in an excess of water that percolates downward through the soil layers. Slow rates of decomposition leads to large amounts of fulvic acid, greatly enhancing chemical weathering. The downward percolation, in conjunction with chemical weathering leaches magnesium (Mg), iron (Fe), and aluminum (Al) from the soil and transports them downward, a process known as podzolization. This process leads to marked contrasts in the appearance and chemistry of the soil layers. Two students learned about soils in school. Brad had to study forest soils, while his colleague Frank had to study grasslands. They both did a good job and received A's for their efforts and accumulated knowledge. Which student read more about a rich diversity of animals?

A: Brad

Problem: Farsightedness, or hyperopia, is the condition in which distant objects are seen clearly, but nearby objects appear blurry. It occurs when the eyeball is shorter than normal (see Figure below ). This causes images to be focused in a spot that would fall behind the retina (if light could pass through the retina). Hyperopia can be corrected with convex lenses. The lenses focus images farther forward in the eye, so they fall on the retina instead of behind it. Two people went to the eye doctor's office for an annual exam; James had farsightedness, while Bob had myopia. Which person had the eyeballs shorter than normal?

A: James

Problem: The Gaia hypothesis states that the biosphere is its own living organism. The hypothesis suggests that the Earth is self-regulating and tends to achieve a stable state, known as homeostasis . For example the composition of our atmosphere stays fairly consistent, providing the ideal conditions for life. When carbon dioxide levels increase in the atmosphere, plants grow more quickly. As their growth continues, they remove more carbon dioxide from the atmosphere. In this way, the amount of carbon dioxide stays fairly constant without human intervention. A scientist with an interesting idea for an experiment begins building a dome. This dome will be completely cut off from the rest of the world. It will produce all of its own resources, breathable air, anything needed to sustain life, putting it into a state of homeostasis. Given the dome experiment is a success and attains homeostasis, will it be in a stable or unstable state?

A:
stable