Classical Rome made significant contributions to modern Western civilization, and among the options provided, the most relevant is:
large infrastructure projects to benefit the public.
Rome was known for its extensive infrastructure, including roads, aqueducts, and buildings, which facilitated trade, communication, and public services. This emphasis on infrastructure development has influenced modern public works and urban planning.
While other options, like the idea of a written constitution and democratic principles, have some roots in Roman law and governance, they are more directly derived from other historical developments, such as the Enlightenment. The direct election of rulers also isn't a practice that aligns closely with the Roman system of government.