Bacillus thuringiensis (Bt) is a soil bacterium used by organic farmers as a natural pesticide. Bt creates a toxin to specific insect larva but is harmless to mammals. The gene for this protein has been genetically engineered into plants to make them insect resistant e.g., Bt cotton (modified to control budworms and bollworms). Delayed ripening technology is to delay the ripening process that causes rotting without affecting natural flavour development. Fruit ripening and softening are caused in part by enzymes. Inhibition of this enzymes activity by expression of antisense mRNA delays the ripening process. Flavr Savr tomato was the first genetically engineered food approved for human consumption in the USA. Thus, the correct answer is option D.