Problem: I can use this background: The earliest members of the human species evolved around 200,000 years ago in Africa. Early humans lived in small populations of nomadic hunters and gatherers. Human beings remained in Africa until about 40,000 years ago. After that, they spread throughout Europe, Asia, and Australia. By 10,000 years ago, the first human beings colonized the Americas. During this long period of time, the total number of human beings increased very slowly. Birth rates were fairly high but so were death rates, producing low rates of population growth. Now, I have a new situation: Two colleagues studied human evolution, Dan studied early humans, from around 200,000 years ago, while Bob studied human settlements from 10,000 years ago. Answer this question please: Which student learned less about nomadic gatherers?

A: Bob

Problem: I can use this background: Chemical equilibrium was studied by French chemist Henri Le Chatelier (1850-1936), and his description of how a system at equilibrium responds to a change in conditions has become known as Le Chatelier's principle . This principle states that when a chemical system is at equilibrium and is disturbed by a stress, the system will respond by attempting to counteract that stress until a new equilibrium is established. Stresses to a chemical system include changes in the concentrations of reactants or products, changes in the temperature of the system, or changes in the pressure of the system. We will discuss each of these stresses separately. In each case, the change to the equilibrium position will cause either the forward or reverse reaction to be favored over the opposite process. When the forward reaction is favored, the concentrations of the products increase, and the concentrations of the reactants decrease. When the reverse reaction is favored, the concentrations of the products decrease, and the concentrations of the reactants increase. Now, I have a new situation: David was conducting experiments on chemical equilibrium in the chemistry lab. First, he took a chemical system that was at equilibrium. He labeled it as case E. Then he changed the temperature of the system. He labeled that experiment as case T. Finally, he observed two more experiments, case A and case B. In case A forward reaction was favored, and in case B reverse reaction was favored. Answer this question please: In which case the products concentration would decrease, case A or case B?

A: case B

Problem: I can use this background: Unfortunately, the layer of good ozone is being destroyed by air pollution. The chief culprits are chlorine and bromine gases. They are released in aerosol sprays, coolants, and other products. Loss of ozone has created an ozone hole over Antarctica. Ozone depletion results in higher levels of UV radiation reaching Earth. In humans, this increases skin cancers and eye cataracts. It also disturbs the nitrogen cycle, kills plankton, and disrupts ocean food webs. The total loss of the ozone layer would be devastating to most life. Its rate of loss has slowed with restrictions on pollutants, but it is still at risk. Now, I have a new situation: Keith is an environmental scientist. He was studying the loss of ozone layer and its effect on different species. His data showed that in the beginning or twentieth century there were hardly any loss of ozone layer. He categorized that time period as time A. Further inquiry revealed that things didn't go well at the end of twentieth century - when there were severe loss of ozone layer. He categorized that time as time B. Answer this question please: At what period would higher level of UV radiation reach earth, time A or time B?

A: time B

Problem: I can use this background: Old age begins in the mid-60s and lasts until the end of life. Most people over 65 have retired from work, freeing up their time for hobbies, grandchildren, and other interests. Stamina, strength, reflex time, and the senses all decline during old age, and the number of brain cells decreases as well. The immune system becomes less efficient, increasing the risk of serious illnesses such as cancer and pneumonia. Diseases such as Alzheimer's disease that cause loss of mental function also become more common. Now, I have a new situation: Two neighboring towns had different demographics. Hill town had younger inhabitants, most of them in their 30's and 40's. Lake town was inhabited by elderly people, most of them above 65 years of age. Answer this question please: Which town had more people that have retired from work?

A:
Lake