Damaged nerves in the spinal cord do not regenerate
themselves naturally, nor even under the spur of
nerve-growth stimulants. The reason, recently dis-
covered, 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.


Could someone please explain? Thanks!

candidly speaking, I chose A, but couldn't exactly relate it to the CR

I vote for B. B states that certain nerve growth stimulants have structure similar to that of antibodies. The stem says that regenration of nerves is not possible even under the spur of nerve growth stimulants.

So B weakens the claim.

A. Will try to explain if correct.

I go with C

C) Nerves in the brain are similar to nerves in the
spinal cord in their inability to regenerate
themselves naturally.

Concusion:
Clearly, then, nerve repair will be a standard medical procedure in the foreseeable future.

this is based on the fact:
Antibodies that deactivate those inhibitors have now been developed.

but the key is here: The concusion saying in general any nerve repair, not specifically saying the spine nerver damage.

C weakens the argument by saying the brain nerves also had the same problem. there might be other problems other than the agents in the spinalcord causing the problem.
we have only the evidence to deactivate the agents in spinal cord and these may not work nerves in brain.

Please let me know your comments on C





The premise says that