When the SARS (Severe Acute Respiratory Syndrome) pandemic occurred in late 2002, officials feared that the outbreak would widespread; they were concerned that the virus would become a global threat and
it would kill vast numbers of patients who would have no protection against it.
(A)
it would kill vast numbers of patients who would have no protection against it.
(B)
it would kill vast numbers of patients with no protection against it.
(C) kill vast numbers of patients who would have no protection against it.
(D) kill vast numbers of patients who have no protection against
them.
(E) kill vast numbers of patients with no protection against
them.
I need help to understand that -
Why the Official Answer is right and why not other?
Choice [A] and [B] are wrong because of the comma splice error. If the second part of the sentence "it would kill vast numbers..." is an independent clause, there must be a comma before "and".
Choice [D] and [E] are wrong because of the improper pronoun usage.