Answer the question

Monarch butterflies use milkweed plants during all of their life stages. Milkweed plants grow in open areas, such as grasslands and wetlands. They also often grow between row crops. Given this information, which of these biotechnologies would pose the greatest threat to monarch butterflies?
Options:
[a]. development of new antibiotics.
[b]. development of new herbicides.
[c]. development of disease-resistant crops.
[d]. development of insect-resistant crops.
[b].