Cotton picking in India is almost entirely performed manually due to indeterminate plant growth, staggered boll bursting requiring multiple pickings, and non-defoliated varieties unsuitable for mechanical spindle pickers. Wheat harvesting is highly mechanized ($\gt 80\%$), while oilseeds and millets are moderately mechanized with reapers and combines. Option analysis: (A) Oil-seeds are harvested using reapers and combines. (B) Cotton harvesting has the lowest level of mechanization in India ($\lt 5\%$). (C) Millets are harvested with reapers. (D) Wheat is one of the most highly mechanized crops.

Registration of a mower knife means that each knife section centers exactly in the guard ledger plate at each dead center of the pitman stroke (or mid-point of stroke is symmetrically positioned between adjacent guards). When outer end is ahead of inner end, it is called 'lead' of cutter bar. Option analysis: (A) Centering of stroke relative to guards defines registration. (B) Outer end ahead of inner end defines cutter bar lead. (C) Alignment with pitman is drive alignment. (D) Level refers to horizontal tilt.

Mechanical grain damage increases significantly when concave clearance is reduced (A) (crushing grains), when cylinder peripheral tip speed is increased (B) (excessive impact energy), and at high moisture levels (C) (susceptible to bruising and internal fissuring). Increased feed rate (E) actually cushions grains and reduces damage. Option analysis: (A) Omits primary impact factors (A) and (B). (B) Omits (A) and (B). (C) Omits (A) and (B). (D) (A), (B) and (C) only represents the factors causing increased grain damage.

Cutter bar knives are traditionally manufactured with smooth edges (C) (which can be resharpened readily and used for fine grass/hay) or under-serrated edges (B) (where serrations on the bottom edge stay sharp longer against ledger plates and prevent straw slippage). According to the official answer key, option 4 '(B) and (C)' is the correct answer. Option analysis: (A) Incomplete. (B) Omits smooth edge. (C) Omits under serrated. (D) (B) and (C) is the designated official answer.