Thanks for the question! I wouldn’t really say this weakens, even if it were true. Let’s take a look at the stimulus: we’re told that a bacteria living in legume plants’ roots produces fixed nitrogen. Then we’re also told that if biotechnology produced wheat strains that roots would host this bacteria, we wouldn’t need as many artificial fertilizers, which supply nitrogen.
Now (D) tells us that legumes are currently the only crops that produce their own supply of fixed nitrogen. This is the wrong answer because it’s not supported that this is an assumption at all; the word “only” makes this answer choice far too strong. Now, as to your specific question of if this weakens the argument, I wouldn’t necessarily say so, because it could be the case that the bacteria produce the nitrogen and the legumes produce the nitrogen, and so if the bacteria produce the nitrogen anyway, then the argument isn’t really weakened. I assume you ask this as separate from the original question.
Hope this helps! Feel free to ask any other questions that you might have.
