In the question given below, a passage is followed by three statements which may or may not be inferred from the passage. Select the correct combination of statements that can be inferred. Passage: A global study found that air quality in urban areas significantly improves when public transportation systems are expanded and made more efficient. Cities with extensive bus and rail networks tend to report lower levels of nitrogen dioxide and particulate matter. The researchers also observed that fewer private vehicles on the road correlated with better respiratory health outcomes in city dwellers. Statements:
I. Expanding public transport may encourage people to use fewer private vehicles.
II. Air pollution in cities is partially caused by private vehicle emissions.
III. All cities with poor air quality have inefficient public transport systems.