The diagram above shows parts of a plough.
Study it and answer this question.
The part labelled I in the diagram is the
 

Study the diagram above and answer question
The crop associated with the diagram above is?
 

During which of the following plant propagation methods is the tool represented used?

Study the diagram above and answer question
The farm tool associated with the diagram above is
 

From the curve above, at what point is it advisable for the farmer to stop further addition of input?