Which one of these is not part of a disc plough?

Planter is not part of a disc plough. A disc plough is a farm implement that is used for primary tillage to break up and loosen soil in preparation for planting. It typically consists of a series of individual discs, which are arranged in a line and mounted on a frame. The coulter is a vertical blade that cuts through the soil and creates a furrow for the discs to follow. The discs themselves are typically concave and have a sharp edge, which slices through the soil and turns it over. The furrow wheel follows behind the discs and helps to control the depth of the ploughing. The disc scraper is a blade or bar that is attached to the frame of the plough and helps to prevent the discs from becoming clogged with soil or debris. It is typically positioned behind the discs and scrapes away any material that may be caught between them. Therefore, the planter is the option that is not part of a disc plough. A planter is a separate implement that is used for planting seeds or seedlings into the soil, and is not typically integrated into the design of a disc plough.