In a time series data, last 4 weeks sales values, in the order of most recent to oldest are $29, $30, $28 and $26. What is the sales forecast for the 5th week using the 3 weeks weighted moving average time series forecasting model if the weighing scheme is 0.5, 0.3 and 0.2 (in the order of most recent to oldest)?

a. 30

b. 29

c. 29.1

d. 29.25