Read the following statements.
I. Recombinant DNA technology is used to improve crop plants by increasing their productivity, by making them more nutritious and by developing disease resistant.
II. Bt cotton is resistant to bollworm infestation.
III. Bacillus thuringiensis forms cry protein during any phase of its growth.
IV. Bacillus thuringiensis is not harmed by self Cry protein because of its occurrence as a protoxin. 
V. Protoxin Cry protein is changed into active Cry protein in the gut of insects due to alkaline pH in the gut.

Choose the correct statements.