Read the following passage and mark the letter A, B, C, or D to indicate correct answer to each of the questions.
India's big cities are facing extremely dangerous levels of air pollution that are hard to imagine. The Air Quality Index (AQI) is used to measure air pollution. A healthy and normal AQI level is 50, but anything over 300 is considered very dangerous to breathe. The AQI website explains that when the level reaches 300, it is a health emergency, and everyone may face serious health problems. On November 8, the city of Chandrapur in Maharashtra recorded an AQI level of 824, making it the most polluted city in India. New Delhi, the capital, had an AQI of 724 on the same day. Environmentalists have described many of these cities as "gas chambers."
A thick, toxic smog covers New Delhi, and people have been advised to wear masks when going outside. Schools in the city were closed for three days to protect students. Pollution is a regular problem in New Delhi because of its nine million vehicles, many of which do not meet emissions standards. Recently, the problem has worsened because of other factors. These include pollution from nearby states, farmers burning straw after harvest, and a lack of wind to blow the smog away.
To address the problem, city officials have taken action. They have sprayed water on roads to prevent dust from rising and banned diesel-powered electricity generators for 10 days, except for use in hospitals and cellphone towers.
