Step 1: Understanding the Concept:
Mechanical crop harvesting relies on specialized mechanisms tailored to the physical traits of the target crop.
Step 3: Detailed Explanation:
Let us review the mechanical harvesting methods for the listed crops:
1.
Potato: Harvested using potato diggers, which lift the tubers from the soil and separate them from soil clods.
2.
Maize: Harvested using corn snappers, pickers, or combine headers that strip the ears from the stalks.
3.
Cotton: Harvested using either cotton strippers or cotton pickers.
A cotton picker uses rotating barbed spindles to pull the open cotton fibers out of the bolls while leaving the main plant foliage intact.
Thus, "picker" as a primary harvesting system is directly related to cotton.
Step 4: Final Answer:
The correct option is 3, which corresponds to Cotton.