A farmer wants to separate grains from their husks after harvesting. Which physical separation method would be most suitable for this purpose, and why?

The most suitable physical separation method for separating grains from their husks is winnowing. This method is based on the principle that grains are heavier than husks. 

When the mixture is dropped from a height in the presence of wind or a fan, the lighter husks are carried away by the wind, while the heavier grains fall straight down, forming a separate pile. 

This technique is effective due to the significant difference in density and weight between the grains and the husks.