When the technique known as gene-splicing was invented in the early 1970's, it was feared that scientists might inadvertently create an "Andromeda strain," a microbe never before seen on Earth that might escape from the laboratory and it would kill vast numbers of humans who would have no natural defenses against it.

(A) it would kill vast numbers of humans who would have no natural defenses against it

(B) it might kill vast numbers of humans with no natural defenses against it

(C) kill vast numbers of humans who would have no natural defenses against it

(D) kill vast numbers of humans who have no natural defenses against them

(E) kill vast numbers of humans with no natural defenses against them

OA C

Source: Official Guide