Which of the following findings, if true, would support critics of gm crops?
a. bt cotton requires farmers to use less insecticide on their fields.
b. bt corn is proven harmless to butterflies.
c. bt corn reduces the populations of bees needed to pollinate the plants.
d. bt cotton produces higher crop yields than other cotton.

The correct answer is letter C, Bt corn reduces the populations of bees needed to pollinate the plants.

Plants that have been genetically modified are not naturally occurring therefore, organisms that are introduced to such kinds of plant breeds are not familiar with that kind of species. The probable side effect that critics would use is the answer to the question because plant pollination is such a critical cycle that occurs within the Earth. If plants are not able to pollinate, its biodiversity would be compromised.