Concept:The part labelled I is a soil-working component, such as a disc or mouldboard, not a supporting or rolling part.
Explanation:Part I performs functions directly related to soil engagement.
It helps in cutting through the soil, inverting the furrow slice, and in some ploughs, pulverizing the slice.
These actions are associated with the working surface of the plough bottom.
However, enabling the plough to roll over obstacles is not a soil-working function.
That function is carried out by a wheel or rolling support mechanism, not by part I.
Therefore, the function that is not associated with the labelled part is rolling over obstacles.
Answer:D. Enabling the plough to roll over obstacles
