According to paragraph 4, which of the following was discovered as a result of scientific and technical investigations of waterpower conducted between 1650 and 1800? A. Some types of small waterwheel can produce as much horsepower as the very largest wheels. B. Waterwheels operate more efficiently when water falls away from their blades slowly than when water falls away quickly. C. Waterwheel efficiency can be improved by increasing the amount of kinetic energy water contains as it passes over a waterwheel's blades. D. Unlike other types of waterwheels, the overshot wheel is capable of producing more than 60 horsepower units of energy.