What Does the Term "Genetically Modified" Mean, in Terms of Crop

What does the term "genetically modified" mean, in terms of crop plants?

A) The genes in a plant are altered, and then the plant is grown to see what the mature crop's traits are.
B) One gene in a plant is changed, and then the plant is grown to maturity.
C) An identified gene is optimized in a plant.
D) An identified gene from one plant is inserted into another.