Answer:
Inserting the gene that produces a substance toxic to insects but harmless to humans into corn plants would result in fewer pesticides needed.
Step-by-step explanation:
The best reason for inserting the gene that controls production of a substance that is toxic to insects but harmless to humans into corn plants would be option C: fewer pesticides will be needed.
By introducing the gene into corn plants, the plants will produce the substance that is toxic to insects, which will help to protect the corn plants from insect damage. As a result, there will be less need for pesticides, which are often used to control insect infestations. This can have significant benefits for both the environment and human health, as the use of pesticides can have negative impacts on the surrounding ecosystem and may pose health risks to humans who consume pesticide-contaminated crops.
Options A and B are unlikely to be affected by the introduction of the gene, as the gene does not directly impact the growth rate or nutrient content of the corn plants. Option D is also unlikely to be affected, as the gene does not introduce any new nutrients into the corn plants.