Final answer:
Option(C)The factor significantly impacting U.S. energy policy and the use of fossil fuels is 'New auto efficiency standards', which promote fuel efficiency in transportation and reduce dependence on oil.
Step-by-step explanation:
The factor that is having a significant impact on U.S. energy policy and the use of fossil fuels, despite the absence of far-reaching energy policy, is C) New auto efficiency standards. These standards are a response to energy security, environmental, and economic concerns that have driven significant increases in fuel economy. This response includes fuel switching from uncertain and volatile foreign oil to domestic electricity and biofuels, and increased production of electricity from low carbon sources.
Transportation is almost completely dependent on oil and internal combustion engines, making it a significant user of primary energy and producer of carbon emissions in the United States. To address environmental concerns such as climate change and to reduce dependency on foreign oil, new auto efficiency standards have been implemented, steering the transportation industry towards more efficient vehicles and alternative energy sources. This shift is economically and politically motivated and represents a major transformative step toward reducing fossil fuel use and embracing more sustainable energy practices. While interest in renewable energy has varied over time in response to oil prices and energy security considerations, auto efficiency standards are a current regulatory measure directly influencing the adoption of cleaner transportation technologies. These standards are set by governmental agencies and directly affect the types of vehicles being produced by the automotive industry, thereby impacting overall energy policy and consumption. This regulatory approach helps facilitate a transition from higher emitting fossil fuel vehicles to more efficient, lower carbon alternatives.