Le Corbusier proposed a city consisting of high-rise buildings with greenbelts for institutions and recreational areas. What is the name of that concept?

The correct concept proposed by Le Corbusier that describes a city comprising high-rise buildings along with greenbelts dedicated to institutions and recreational spaces is known as "La Cité Radieuse." This principle envisioned a functionalist urban planning model that prioritized the organization of living spaces, nature, and urban facilities.

La Cité Radieuse, which translates to "The Radiant City," emphasized the importance of modern architecture influenced by the needs of the urban population, highlighting the integration of green spaces within the urban fabric. The design sought to optimize sunlight exposure, air circulation, and community interaction, making the city more livable and sustainable.

The other terms mentioned do not encapsulate this broader urban vision as effectively as La Cité Radieuse. "Le Moderne" refers more generally to modernist architecture rather than a specific urban plan. "Le Contemporaine" does not specifically relate to Le Corbusier's work, and "Unité d'Habitation" pertains specifically to a housing unit design that focused on residential architecture rather than an entire city layout.