What was one of the key focuses of TEA-21 concerning transportation?

Answer: C — Strengthening transportation safety

One of the key focuses of TEA-21, or the Transportation Equity Act for the 21st Century, was strengthening transportation safety. This legislation emphasized the importance of enhancing the safety of the nation's transportation infrastructure, which included measures to reduce vehicle-related accidents and increase the safety of public roads. It allocated funding for safety programs, research, and initiatives specifically designed to improve safety standards across various modes of transportation, including highways and public transit systems. This focus on safety is crucial, as it not only protects individuals on the road but also contributes to the overall efficiency and reliability of the transportation systems. By prioritizing safety, TEA-21 aimed to create a safer environment for all road users, which is a fundamental aspect of effective transportation policy. Other options, while important in their own respects, do not encapsulate the primary focus of TEA-21 as decisively as strengthening safety does.