Bt cotton is a genetically modified variety of cotton producing an insecticide. Bt indicates the bacterium, Bacillus thuringiensis.
The process by which protoplasts of two different plant species fuse together to form hybrids is known as somatic hybridisation.
A genetically modified tomato, or transgenic tomato is a tomato that has had its genes modified, using genetic engineering. The first commercially available genetically modified food was a tomato engineered to have a longer shelf life (the Flavr Savr).
Thus, the correct answer is option C.