Answer:
The correct answer would be "The engineered genes in the crops could be transferred to wild varieties of the plants".
Genetically modified (GM) crops are those in which foreign gene or gene of interest is inserted from organism of other species.
One of biggest disadvantage of GM crops is that the gene could transfer to the wild variety of the plant.
As crops share fields with other crops including weeds, genes can transfer from selected crop to other species such as wild variety, weeds, or any other crop.
It may result in the development of resistance against herbicides, pesticides et cetera in unwanted plants.