Critical Reasoning

Damaged nerves in the spinal cord do not regenerate themselves naturally, nor even under the spur of nerve-growth stimulants. The reason, recently discovered, is the presence of nerve-growth inhibitors in the spinal cord. Antibodies that deactivate those inhibitors have now been developed. Clearly, then, nerve repair will be a standard medical procedure in the foreseeable future.

Which of the following, if true, casts the most serious doubt on the accuracy of the prediction above?

(A) Prevention of the regeneration of damaged nerves is merely a by-product of the main function in the human body of the substances inhibiting nerve growth.
(B) Certain nerve-growth stimulants have similar chemical structures to those of the antibodies against nerve-growth inhibitors.
(C) Nerves in the brain are similar to nerves in the spinal cord in their inability to regenerate themselves naturally.
(D) Researchers have been able to stimulate the growth of nerves not located in the spinal cord by using only nerve-growth stimulants.
(E) Deactivating the substances inhibiting nerve growth for an extended period would require a steady supply of antibodies.

OA after some discussion.

B[/spoiler]

IMO A .

(A) Prevention of the regeneration of damaged nerves is merely a by-product of the main function in the human body of the substances inhibiting nerve growth. -- [Weakens the argument by giving a reason why the technique would not be positive ]
(B) Certain nerve-growth stimulants have similar chemical structures to those of the antibodies against nerve-growth inhibitors. -- [similar structure has nothing to do about the argument so consider it as OOS]
(C) Nerves in the brain are similar to nerves in the spinal cord in their inability to regenerate themselves naturally. -- [This too is irrelevant or simple OOS to discuss]
(D) Researchers have been able to stimulate the growth of nerves not located in the spinal cord by using only nerve-growth stimulants. -- [This is not weakening the argument ]
(E) Deactivating the substances inhibiting nerve growth for an extended period would require a steady supply of antibodies. -- [Its tells about some extra requirements after implimentation of technique , doesnt highlight any flaw .]

OOS --> Out of Scope

Agreed with AIM GMAT

OA has to be A

Just for curosity,what is the OA for this one?