Modern public transportation systems often rely on extensive networks of buses, subways, and trains to connect urban populations with essential services and job opportunities. However, maintaining these systems can be challenging. Through key investments and innovative strategies, cities can improve their transportation infrastructure. For instance, encouraging the use of clean energy sources can reduce operational costs and environmental impact. Additionally, cities can implement smart technology to optimize route efficiency.
To enhance the flow of ideas in the passage, which of the following sentences would best fit the logical flow of information presented above?