PART a
If Allergies Are Caused by Viruses, Then

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: a. $\begin{array}{l}\text { All } A \text { are } V \text {. } \\\text { No } A \text { are } D \text {. } \\\hline\text { No } V \text { are } D \text {. }\end{array}$$\quad$ b. $\begin{array} { l } \text {If \( A \) then \( V \). }\\ \text { {Not} V}\\ \hline\text { {Not} A}\\\end{array}$$\quad$ c. $\begin{array} { l } \text {{Not} V }\\ \text { {Not} A}\\ \hline\text {If \( A \) then \( V \). }\\\end{array}$

d. $\begin{array} { l } \text {If \( A \) then \( V \). }\\ \text {{Not} A }\\ \text { {Not} V}\\\end{array}$$\quad$ e. $\begin{array} { l } \text {If \( \mathrm{A} \) are \( \mathrm{C} \) then \( \mathrm{V} \operatorname{can} \mathrm{D} \). }\\ \text { \( A \) are not C.}\\ \text {\( V \) cannot \( D \). }\\\end{array}$ 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.