Correct Option
The correct option is (a).
Explanation
Winnowing is a separation technique used in agriculture to separate heavier components of a mixture from lighter components using wind or blowing air. It is primarily performed after the threshing process to isolate grains from husks and hay.
Statement-wise Analysis
- Statement 1 is Correct: Winnowing is the process of separating heavier grains from lighter chaff. When the mixture is dropped from a height, the heavier grains fall vertically to the ground, forming a heap, while the lighter chaff is carried away by the wind.
- Statement 2 is Incorrect: This method is typically employed by farmers with small landholdings. Farmers with large landholdings usually utilize combine harvesters, which are integrated machines that perform harvesting, threshing, and winnowing simultaneously, rendering manual winnowing unnecessary.
- Statement 3 is Incorrect: Winnowing relies on wind or air currents, not water currents. The physical principle involved is the difference in weight between the grain and the chaff in the presence of moving air. Separation techniques involving water include sedimentation or decantation.
Key Takeaway: Winnowing is a wind-assisted separation method used to separate lighter chaff from heavier grains, predominantly practiced by small-scale farmers.