Anna$$S department uses exponential smoothing to make forecasts. Given the last period$$s demand forecast was for $20,000$ units and last period$$s actual demand was $21,000$ units, what should be the forecast for the current period? $($Anna$$s department uses a smoothing constant $(\backslash$alpha $)$ equal to $0\mathrm{.}40.)$

A$.21,000$ B$.20,600$ C$.20,400$ D$.20,000$