Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.

The garden city was largely the invention of the British social visionary Ebenezer Howard (1850-1928). After emigrating from England to the USA, and an unsuccessful attempt to make a living as a farmer, he moved to Chicago, where he saw the reconstruction of the city after the disastrous fire of 1871. In those pre-skyscraper days, it was nicknamed “the Garden City”, almost certainly the source of Howard's name for his proposed towns. Returning to London, Howard developed his concept in the 1880s and 1890s, drawing on ideas that were circulating at the time, but creating a unique combination of proposals. The nineteenth-century slum city was in many ways a horrific place; but it offered economic and social opportunities, lights and crowds. At the same time, the British countryside - now too often seen in a sentimental glow - was in fact equally unprepossessing: though it promised fresh air and nature, it suffered from agricultural depression and it offered neither enough work and wages, nor adequate social life. Howard's idea was to combine the best of town and country in a new kind of settlement, the garden city. Howard's idea was that a group of people should establish a company, borrowing money to establish a garden city in the countryside, far enough from existing cities to ensure that the land was bought at the bottom price. They should get agreement from leading industrialists to move their factories there from the congested cities; their workers would move too, and would build their own houses. Garden cities would follow the same basic blueprint, with a high proportion of green spaces, together with a central public open space, radial avenues, and peripheral industries. They would be surrounded by a much larger area of permanent green belt, also owned by the company, containing not merely farms, but institutions like reformatories and convalescent homes, that could benefit from a rural location. As more and more people moved out, the garden city would reach its planned limit - Howard suggested 32,000 people; then, another would be started a short distance away. Thus, over time,there would develop a vast planned house collection, extending almost without limit; within it, each garden city would offer a wide range of jobs and services, but each would also be connected to the others by a rapid transportation system, thus giving all the economic and social opportunities of a big city.

The word “They” in paragraph 3 refers to _______. A. garden cities B. green spaces C. avenues D. industries