Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.
--------
Question: Context: The major cause of outdoor air pollution is the burning of fossil fuels. Fossil fuels are burned in power plants, factories, motor vehicles, and home heating systems. Ranching and using chemicals such as fertilizers also cause outdoor air pollution. Erosion of soil in farm fields, mining activities, and construction sites adds dust particles to the air as well. Some specific outdoor air pollutants are described in Table 25.1. Air Pollutant Sulfur oxides Nitrogen oxides Carbon monoxide Carbon dioxide Particles (dust, smoke) Mercury Smog Ground-level ozone Source coal burning motor vehicle exhaust motor vehicle exhaust all fossil fuel burning wood and coal burning coal burning coal burning motor vehicle exhaust Problem acid rain acid rain poisoning global climate change respiratory problems nerve poisoning respiratory problems respiratory problems Outdoor air pollution causes serious human health problems. For example, pollutants in the air are major contributors to respiratory and cardiovascular diseases. Air pollution may trigger asthma attacks and heart attacks in people with underlying health problems. In fact, more people die each year from air pollution than automobile accidents. Air pollution may also cause acid rain. This is rain that is more acidic (has a lower pH) than normal rain. Acids form in the atmosphere when nitrogen and sulfur oxides mix with water in air. Nitrogen and sulfur oxides come mainly from motor vehicle exhaust and coal burning. If acid rain falls into lakes, it lowers the pH of the water and may kill aquatic organisms. If it falls on the ground, it may damage soil and soil organisms. If it falls on plants, it may make them sick or even kill them. Acid rain also damages stone buildings, bridges, and statues, like the one in Figure 25.1. Another major problem caused by air pollution is global climate change. Gases such as carbon dioxide from the burning of fossil fuels increase the greenhouse effect and raise Earths temperature. The greenhouse effect is a natural feature of Earths atmosphere. It occurs when certain gases in the atmosphere, including carbon dioxide, radiate the suns heat back down to Earths surface. Figure 25.2 shows how this happens. Without greenhouse gases in the atmosphere, the heat would escape into space. The natural greenhouse effect of Earths atmosphere keeps the planets temperature within a range that can support life. The rise in greenhouse gases due to human actions is too much of a good thing. It increases the greenhouse effect and causes Earths average temperature to rise. Rising global temperatures, in turn, are melting polar ice caps and glaciers. Figure 25.3 shows how much smaller the Arctic ice cap was in 2012 than it was in 1984. With more liquid water on Earths surface, sea levels are rising. Adding more heat energy to Earths atmosphere also causes more extreme weather and changes in precipitation patterns. Global warming is already causing food and water shortages and species extinctions. These problems will only grow worse unless steps are taken to curb greenhouse gases and global climate change. You may be able to avoid some of the health effects of outdoor air pollution by staying indoors on high-pollution days. However, some indoor air is just as polluted as outdoor air. One source of indoor air pollution is radon gas. Radon is a radioactive gas that may seep into buildings from rocks underground. Exposure to radon gas may cause lung cancer. Another potential poison in indoor air is carbon monoxide. It may be released by faulty or poorly vented furnaces or other fuel-burning appliances. Indoor furniture, carpets, and paints may release toxic compounds into the air as well. Other possible sources of indoor air pollution include dust, mold, and pet dander. Its easier to control the quality of indoor air than outdoor air. Steps home owners can take to improve indoor air quality include: keeping the home clean so it is as free as possible from dust, mold, and pet dander. choosing indoor furniture, flooring, and paints that are low in toxic compounds such as VOCs (volatile organic compounds). making sure that fuel-burning appliances are working correctly and venting properly. installing carbon monoxide alarms like the one in Figure 25.4 at every level of the home.
Question: __toxic gas that may be released by faulty fuel-burning appliances

Answer: carbon monoxide

Question: Context: One day Mr. White gave his wife ten pounds for her birthday -- ten new pound notes. So Mrs. White went out shopping. She waited for a bus, got on it and sat down next to an o1d 1ady. After a while, Mrs. White noticed that the old 1ady's handbag was open. Inside it, she saw a wad of pound notes exactly like the ones her husband had given her. So she quickly looked into her own bag -- the notes had gone! Mrs. White was sure that the o1d lady next to her had stolen them. She immediately thought of calling the police. But as she disliked making a fuss , she decided to take back the money from the old 1ady's hand bag and say nothing about it. She looked around to make sure nobody was watching. Then she carefully put her hand into the o1d lady's bag, took the notes, and put them into her own handbag. When she got home that evening, Mrs. White showed her husband the beautiful hat she had bought. "How did you pay for it?" Mr. White asked. "With the money you gave me for my birthday, of course" she answered. "Oh? What's that, then?" he asked, as he pointed to a wad of pound notes on the table.
Question: What did Mrs. White use the money given by her husband for?

Answer: nothing.

Question: Context: As of the census of 2000, there were 325,957 people, 149,937 households, and 94,460 families residing in the county. The population density was 570 people per square mile (220/km2). There were 182,467 housing units at an average density of 319 per square mile (123/km2). The racial makeup of the county was 92.65% Race (United States Census), 4.18% Race (United States Census) or Race (United States Census), 0.22% Race (United States Census), 0.77% Race (United States Census), 0.03% Race (United States Census), 1.14% from Race (United States Census), and 1.02% from two or more races. 4.34% of the population were Race (United States Census) or Race (United States Census) of any race. 89.7% spoke only English language at home; 4.4% spoke Spanish language, 1.3% German language, and 1.0% French language at home.
Question: Which group is smaller for the county according to the census: people or households?

Answer:
households