Assume the price of salt increased from $0.30 in 1985 to $0.50 in 1995. if we calculate the average rate of price increase for salt over this period, we could accurately say: a. the real price of salt definitely increased during the period. b.the price of salt increased at about a 20% rate per year during this period. c.the price of salt increased by about 20% total during this period. d.the price of salt increased at about a 5% rate per year during this period. e.the price of salt increased at about a 40% rate per year during this period.