What type of aid is provided to enhance the infrastructure of a country, such as building roads or hospitals?

Development aid is specifically aimed at improving the economic development and welfare of a country, targeting aspects such as infrastructure, education, health, and governance. This type of aid is typically invested in long-term projects, such as constructing roads and hospitals, which are crucial for a nation's growth and improved quality of life.

While tied aid, multilateral aid, and bilateral aid can also be forms of development support, they are characterized by additional conditions or specific relationships. Tied aid is assistance given with the stipulation that it must be used to purchase goods or services from the donor country, which can limit its flexibility in addressing the recipient's specific needs. Multilateral aid involves contributions from multiple countries or organizations and may be used for broader initiatives rather than direct infrastructure projects. Bilateral aid is given directly from one country to another, which can also support infrastructure but is often contingent on political relationships and may not always prioritize the enhancement of infrastructure as a primary goal.

In this context, development aid stands out as the most encompassing and relevant category for projects aimed at enhancing infrastructure.