Bacteria were some of the first organisms to be genetically modified because they have a relatively small genome and reproduce quickly. All of the following are reasons to
study and modify a bacterial cell's genome for beneficial uses except
to use bacteria cells as a vector to add genes that code for useful products.
O to determine the genes that code for proteins such as those used to produce insulin in large
amounts.
O to modify bacteria into an infectious form that has the ability to mutate quickly.
to determine genes that code for toxins against other bacterial cells to make antibiotics from
these toxins.

To modify bacteria into an infectious form that has the ability to mutate quickly

Explanation:

Genetic modification has given us many useful discoveries. In the given question, you are given several of them related to the genetic modification of bacteria. The only harmful example you were given is the third one.

If someone modifies bacteria into an infectious form, they will spread more quickly and easily. That would lead to many people getting ill and possibly dying. Also, the faster bacteria mutate, the harder they are to deal with. This means that one type of antibiotic wouldn't be enough to cure all people who are ill. There is a possibility that new antibiotics would have to be invented, which takes time and research.

This is why the third option is the correct one.