Concept:Mechanical power refers to the use of tractors, engines, and machines to carry out farm work.
Some operations are done more safely and precisely by human hands.
Explanation:Soil tillage can be done with tractors and ploughs, so mechanical power is useful here.
Fertilizer application can be done using mechanical spreaders and sprayers.
Planting of seeds can also be done with mechanical planters.
Staking of yams requires careful tying and positioning of stakes around each yam plant.
This delicate work is normally performed manually by farm workers.
Therefore, mechanical power is not usually required for staking of yams.
Answer:C. staking of yams