Plasmids are used as vectors in plant and bacterial genetic engineering. However, there is a major difference in the fate of genes introduced into bacteria on most bacterial plasmids and into plants on tumor-inducing (Ti) plasmids. What is this difference?

A. Bacterial plasmids and the genes they carry usually are not integrated into the chromosome; Ti plasmids and the genes they carry are integrated into the chromosome.

B. Gene expression tends to decrease rapidly and unpredictably in bacteria; gene expression is much more stable in plants.

C. Bacterial plasmids are circular DNAs; Ti plasmid DNA is linear.

D. Bacterial plasmids typically do not modify the growth of the host cells; Ti plasmids modified for genetic engineering always produce plant galls.

E. In bacteria, genes are stably expressed; in plants, gene expression is always lost quickly.