I think it’s E (microtubules) i can be wrong but hopefully this helped
<span>Some 120 prescription drugs sold worldwide today are derived directly from rainforest plants. And according to the U.S. National Cancer Institute, more than two-thirds of all medicines found to have cancer-fighting properties come from rainforest plants. Examples abound. Ingredients obtained and synthesized from a now-extinct periwinkle plant found only in Madagascar (until deforestation wiped it out) have increased the chances of survival for children with leukemia from 20 percent to 80 percent.</span>
The answer is C) Cloning eliminates the ability to sexually reproduce and provide genetic variability.
In the future, there is no variability in the genes in the clones given that they are the exact copies of the "parent" produce. All should be identical without differences and variations. Although Farmer Brown doesn't want this to happen that's is what he is reluctant to listen to Farmer Green's advice.