Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information. A. Until more studies are done, suggestions about the causes of precipitation in cities will focus on the roughness of terrain rather than on surface air and convergence. B. Certain phenomena of city landscapes, such as large structures, cause surface air to slow and converge, which brings a change in weather patterns to cities and rural areas. C. One reason why precipitation may be greater in cities than in the countryside is that large buildings that are found in cities cause surface air to slow and converge. D. Studies that focus on large structures, which are only partly responsible for the increased roughness of city terrain, are incomplete in their explanation of increased precipitation.