Concept:A disc plough is used for primary tillage, while a disc harrow is used for secondary tillage.
Explanation:A disc plough has a few large discs fixed far apart on individual frames.
Each disc works independently to cut and turn the soil deeply.
A disc harrow has many smaller discs fitted close together in gangs.
It is used to break soil clods and level the field after ploughing.
Therefore, the main difference is the spacing of the discs, not their number or size.
Answer:Option B: discs in disc plough are spaced far apart than in disc harrow.