The correct option is D Winnowing
To separate a mixture where the components differ in weight, winnowing is used. To carry out winnowing, wind is blown while the mixture is released from a height. This blows away the lighter component, while the heavier component falls down.
Since husk is very light as compared to barley, when wind blows, it gets carried away by the wind. Hence, winnowing is used to separate husk from a mixture of barley and husk.