Filtration is a mechanical solid-liquid separation operation in which a slurry or suspension is passed through a porous filtering medium (cloth, membrane, or bed) that retains insoluble suspended solid particles while allowing the clarified liquid (filtrate) to pass through.

Working principle of the spiral gravity separator:
(A) True: A spiral separator operates stationary without power, utilizing gravitational and centrifugal forces to separate round/spherical seeds (such as mustard, rape, vetch, and soybean) from oblong, flat, or irregularly shaped wheat and oat kernels.
(R) True: The operating mechanism is based precisely on seed roundness/sphericity. As seeds slide down the helical flights, spherical grains roll faster and gather sufficient centrifugal velocity to fly over the outer rim into an outer discharge flight, whereas flat/elongated grains stay close to the inner core flight.
Since (R) directly explains the physical mechanism governing the operational application stated in (A), option 1 is the correct answer.

In abrasive carborundum peeling (commonly used for potatoes, carrots, and root vegetables), vegetables are rotated against abrasive rollers or linings. A continuous spray of water is injected into the peeler throughout operation to continuously flush out abraded skin fragments, keep the abrasive surfaces unclogged, and minimize frictional heating.

Option analysis:

• Abrasive peeling: Correct, continuous water flushing is intrinsic to the peeling operation.
• Flame peeling: Performed dry at $1000^\circ\text{C}$ in furnace (washing follows afterwards).
• Lye peeling: Involves immersion in hot caustic soda solution followed by separate washing.
• Flash steam peeling: High-pressure steam vessel operation where skin is blasted off by flashing vacuum, followed by separate washing.