Which definition or statement best applies to "Sustainability":
a. though there is much debate as to what the word actually suggests, we can put forth the definition offered by the World Commission on Environment and Development: "Meeting the needs of the present without compromising the ability of future generations to meet their own needs."
b. a group of architects and urban designers in the 1960s within the context of London, who proposed "walking cities" and seductive appeal of space-age imagery.
c. an interdisciplinary method of studying all the evidence, material and immaterial, of documents, artifacts, stratigraphy and structures, human settlements and natural and urban landscapes, created for or by industrial processes.
d. a particular strategy presented by Alejandro Aravena for building better cities, as noticed in his TED TALK.