Correct answer choice (A) tells us that it is "impossible" to escape the lab. So there is no possibility of escape and ever be outside of the lab and interact with other organisms.
Incorrect answer choice (D) tells us they are ALREADY outside of the lab, interacting with whatever other organisms are at the waste treatment facility (and there are a lot of bacteria in waste.) Not being able to escape a specific environment that is already outside of the lab where they are already interacting with other organisms is not what the critics want to happen.
Hope that helps and happy studying,
Nate, LSATMax Instructor