Explanation
Chlorofluorocarbons (CFCs) are a type of compound that was widely used in the 20th century in various applications, including as a refrigerant in air conditioning systems such as centrifugal chillers. CFCs are known to deplete the ozone layer when released into the atmosphere, and their use has been phased out in many countries under the Montreal Protocol. References: LEED Green Associate Candidate Handbook, U.S.
Green Building Council resources

High reflectance roofing materials can help reduce heat gain and peak air temperatures by reflecting more sunlight away from the building, thereby reducing the amount of heat absorbed by the roof. This can lead to lower cooling loads and energy use for air conditioning. Reference: LEED Green Associate Candidate Handbook, U.S. Green Building Council resources

An existing LEED certified building located on a college campus is eligible for LEED for Building Operations and Maintenance; Existing Buildings (LEED O+M: EB). This rating system applies to existing buildings that are undergoing improvement work or little to no construction. It focuses on measuring and improving the performance of building operations and maintenance practices in areas such as energy efficiency, water conservation, waste management, indoor environmental quality, transportation, and occupant satisfaction. To be eligible for LEED O+M: EB, a project must meet certain minimum program requirements (MPRs), such as having a reasonable site boundary, being in a permanent location on existing land, being fully operational and occupied for at least one year prior to certification application, and complying with environmental laws and regulations. Reference: LEED certification for existing buildings and spaces6; Maintaining certification7; LEED v4: Building Operations + Maintenance Guide4

Explanation
A wind turbine is a source of green power, which is electricity generated from renewable sources that have low or zero greenhouse gas emissions. A wind turbine converts the kinetic energy of the wind into mechanical power, which can then be used to generate electricity. Wind power is a clean, abundant, and sustainable form of energy that does not produce air pollution or contribute to climate change. According to the U.S.
Department of Energy, wind power accounted for about 8.4% of the total U.S. electricity generation in 2020.
The other options are not sources of green power, as they either rely on fossil fuels or nuclear energy, which have significant environmental and social impacts. Clean coal is a term used to describe technologies that aim to reduce the emissions and waste from burning coal, but it is still a carbon-intensive and polluting source of energy. Nuclear fission is a process that splits atoms to release energy, but it also produces radioactive waste that poses long-term health and safety risks. Natural gas captured by hydraulic fracturing, or fracking, is a process that injects water, chemicals, and sand into underground rock formations to release natural gas, but it also causes water contamination, air pollution, and seismic activity. References: LEED v4 Reference Guide for Building Design and Construction, p. 347 1; [U.S. Department of Energy website]