(A) is incorrect because having primitive or simple genetic constructions does not weaken the argument that the bacteria is safe -- in fact, having simple genes may make them safer and less likely to have dangerous genes.
(B) although this seems tempting, that it may be dangerous to use parasitic bacteria, the proponents are asking to alter these genes and make these bacteria less dangerous, so this would not weaken the argument.
(C) mass production does not make the bacteria more or less safe.
(D) specifically says "to prevent harmful characteristics" bad genes also "must be present" which means the bacteria will always be dangerous
(E) says that there is not much chance of widespread bacteria danger if we are careful, so this strengthens the argument if anything.
Hope that helps and happy studying,
Nate, LSATMax Instructor