Based on the bullwhip effect, what happens when there is variability$/$changes downstream of the supply chain?

Question $19$ options:

A$)$

The upstream processes are able to better serve the end customers

B$)$

The end product cost decreases

C$)$

The upstream entities$/$suppliers$,$ like raw material suppliers $($etc$.),$ suffer an exponential increase in variability$/$error in their planning$/$forecasting efforts

D$)$

There is always an increase in the accuracy of the forecasts being managed by upstream entities$/$companies