To determine the consumer price index (CPI), _____. a. only the current market basket at current prices needs to be known. b. the values of the base-year market basket at current and base-year prices need to be known. c. the values of the current market basket at current and base-year prices need to be known. d. only the current market basket at base-year prices needs to be known. e. the values of the current market basket at current prices and the base-year market basket at base-year prices need to be known.