Schools are typically large buildings that require large amounts of energy to meet students' learning needs. While most of the energy is necessary to maintain safe, comfortable, and interactive learning environments for students, there are ways schools can reduce energy use without affecting students. Which idea will reduce a school's energy usage the most and have the least effect on students? A) Replace classroom computers with encyclopedia sets for conducting research, and replace interactive white boards with dry-erase white boards. B) Cafeteria workers can cook students' breakfast and lunch meals outside on charcoal grills, instead of inside with the electric stovetops and ovens. C) Remove half of the lightbulbs in each classroom and allow students can bring battery-powered flashlights to use for reading small print when needed. D) While the school is closed for holiday breaks, central heat/air systems should be turned off, and unsused electrical items in classrooms should be unplugged.