Years ago, consumers in Frieland began paying an energy tax in the form of two Frieland pennies for each unit of energy consumed that came from nonrenewable sources. Following the introduction of this energy tax, there was a steady reduction in the total yearly consumption of energy from nonrenewable sources. If the statements in the passage are true, then which of the following must on the basis of them be true? ['There was a steady decline in the total amount of energy consumed each year in Frieland.', 'There was a steady decline in the yearly revenues generated by the energy tax in Frieland.', 'There was a steady increase in the use of renewable energy source in Frieland.', 'The use of renewable energy sources in Frieland greatly increased relative to the use of nonrenewable energy sources.']