In forecasting, what's the difference of a "moving average forecast" and a "weighted moving average forecast"? A) The moving average calculates an accumulative average since period 1 to the current period while the weighted moving average only looks at the last 3 periods B) In the weighted moving average forecast, the previous time period has more emphasis than all other time periods C) In the moving average forecast, the last three time periods are always used while the weighted moving average always used five time periods D) In the weighted moving average forecast, certain time periods are emphasized; in the moving average, all time periods have the same weight when the average value is calculated