The correct option is C Alkaline pH of gut
Bt cotton is produced by introducing an endotoxin producing gene from B. thuringiensis. Once Bt cotton grows, it starts producing these toxins. This toxin enters the bollworm when they feed on cotton leaves. Upon reaching the alkaline environment of the insect’s midgut the toxin is activated and binds to specific receptors present on the lining cells. This causes autodigestion and creates holes in the midgut region leading to the death of the insect.