Final answer:
The disadvantage of genetic engineering in the provided options is the potential for unintended consequences, which can affect ecosystems and human health despite the benefits of increased crop yields and pest resistance.
Step-by-step explanation:
The disadvantage of genetic engineering mentioned from the available options is C) Potential for unintended consequences. While genetic engineering has the potential to increase crop yields, enhance resistance to pests, and create crops with better nutritional value, it also carries the risk for unintended outcomes. Such outcomes may include but are not limited to gene transfer to non-target species, the evolution of pest resistance, or effects on non-target organisms, all of which could impact ecosystems and human health. In agriculture, while genomics can be used to generate new hybrid strains, improve disease resistance, and improve both crop yield and quality, the application of genetic engineering must be carefully managed to mitigate potential risks.