PART a If Allergies Are Caused by Viruses, Then a Vaccine

Short Answer

PART A If allergies are caused by viruses, then a vaccine can be developed. Thus, a vaccine cannot be developed, because allergies are not caused by viruses.
The form of this argument is: PART B
Which of the following substitutions proves the argument invalid?
A) A = cats, C = animals, V = dogs, D = climb trees.
B) A = Napoleon was killed in a plane crash. V = Napoleon is dead.
C) A = Robert was assassinated, V = Robert is dead.
D) A = cats, V = animals, D = mammals.
E) A = Shakespeare suffered a heart attack, V = Shakespeare is dead.