Classify the following vaccines by type. Which could cause the disease it is supposed to prevent?
a. attenuated measles virus
b. dead Rickettsia prowazekii
c. Vibrio cholerae toxoid
d. hepatitis B antigen produced in yeast cells
e. purified polysaccharides from Streptococcus pyogenes
f. H. influenzae polysaccharide bound to diphtheria toxoid
g. a plasmid containing genes for influenza A protein