Which of the following is NOT one of the six LEED categories?

The correct choice is C, as "Sustainable design" is not explicitly listed as one of the six LEED categories. The LEED (Leadership in Energy and Environmental Design) framework, developed by the U.S. Green Building Council, consists of specific categories that focus on various aspects of sustainable building practices. These categories are Energy and Atmosphere, Indoor Environmental Quality, Sustainable Sites, Water Efficiency, Materials and Resources, and Location and Transportation.

By including distinct categories like Energy and Atmosphere and Indoor Environmental Quality, LEED provides a structured approach to assess a building's environmental performance and its impact on human health. "Sustainable design" is a concept that influences these categories but does not stand alone as a specific category within LEED's framework.