Many farmers now grow insect-resistant varieties of cotton. the gene for the favorable trait, in this case, insect resistance, is transferred to the cotton's dna using
a: viral vectors.
b: tissue culture.
c: bacterial plasmids.
d: in vitro fertilization.

The correct answer would be C: bacterial plasmids.

In plants, genetic transformation is usually achieved with the help of bacterial plasmid, especially Ti plasmid.

Ti plasmid is a tumor-inducing plasmid generally present in Agrobacterium tumifaciens. This bacteria has a natural ability to infect plant cells and caused tumors or crown gall disease in them. It is also known as natural genetic engineering of plants.

The modified or non-virulent Ti plasmid is used to transfer the gene of interest in the plants.