Amoldboard was a feature and technological development of what device

The moldboard is a curved iron wedge formed by the curved part of a steel plow blade that turns the furrow used to lift and turn the soil.
A moldboard was a feature and technological development of the device plow.
It was used in farming for initial cultivation of soil, for preparation for sowing seed or planting to loosen or turn the soil. 

Ithink the answer is d hope it