What is often required under state law to ensure financing costs are minimized?

The correct answer is the bond referendum. A bond referendum is a public vote that allows citizens to decide whether to approve the issuance of bonds for capital projects. State laws often mandate that large-scale borrowing through bonds be put to a referendum to ensure transparency and public backing for the funds being raised. This process helps to ensure that financing costs are minimized, as it typically leads to more favorable interest rates and terms based on the public's support and confidence in the proposed projects. By requiring voter approval, the state can also ensure that the projects align with the community’s needs and priorities, which can help improve fiscal responsibility and financial planning.

In contrast, a budget proposal primarily outlines how funds will be allocated but does not directly relate to minimizing financing costs. A public opinion survey, while potentially informative as a tool for gauging support for projects, does not serve a formal function in financing or legal requirements. Lastly, a capital improvement plan is essential for strategic planning and prioritizing projects, but it does not inherently involve voter approval or directly influence the financing costs related to bonds.