Medical researcher: Asexpected, records covering
the last four years of ten major hospitals
indicate that babies born prematurely were
more likely to have low birth weights and to
suffer from health problems than were babies
not born prematurely. These records also
indicate that mothers who had received
adequate prenatal care were less likely to have
low birth weight babies than were mothers who
had received inadequate prenatal care.
Adequate prenatal care, therefore, significantly
decreases the risk of low birth weight babies.
Which one of the following, if true, most weakens the
medical researcher's argument?
(A) The hospital records indicate that many babies
that are born with normal birth weights are
born to mothers who had inadequate prenatal
care.
(B) Mothers giving birth prematurely are routinely
classified by hospitals as having received
inadequate prenatal care when the record of
that care is not available.
(C) The hospital records indicate that low birth
weight babies were routinely classified as
having been born prematurely.
(D) Some babies not born prematurely, whose
mothers received adequate prenatal care,
have low birth weights.
(E) Women who receive adequate prenatal care are
less likely to give birth prematurely than are
women who do not receive adequate prenatal
care.

the OA is B [spoiler]but for me


both B and C are correct and weakens the arguments

the premises are as follow
indadequate prenatal care------->premature birth
premature Birth ------->low weighs

Conclusion
inadequate prenatal care----->low weigh

B weakens the conculsion from the first side
C weakens the conclusion from the second side
[/spoiler]
Please any hint would be highly appreciated!!!

Thanks