cryIAb encodes a protein that controls the growth of

The correct answer is Option (3) → Corn borers

Option (3) Corn borers — Correct. Of the options, only corn borers are controlled by the protein of cryIAb; the proteins of cryIAc and cryIIAb act on cotton bollworms.

NCERT Extract:
Biotechnological Applications in Agriculture – “… Specific Bt toxin genes were isolated from Bacillus thuringiensis and incorporated into the several crop plants such as cotton (Figure 10.1). The choice of genes depends upon the crop and the targeted pest, as most Bt toxins are insect-group specific. The toxin is coded by a gene cryIAc named cry. There are a number of them, for example, the proteins encoded by the genes cryIAc and cryIIAb control the cotton bollworms, that of cryIAb controls corn borer.”