$."$We invited students in a college dormitory to sample new Way$-$Q$-$Up Soda. Over $90$ percent found this perky new drink delicious. If you need more energy for work $($or for fun$),$ we have what you need to Way$-$Q$-$Up$."$

Which one of the following statements is the most serious criticism of the above advertisement?

a$.$ College students are not necessarily representative of the general population.

b$.$ Other sodas are just as perky and delicious as Way$-$Q$-$Up$.$

c$.$ The fact that college students found Way$-$Q$-$Up delicious does not mean that it perked them up$.$

d$.$ The fact that students enjoyed Way$-$Q$-$Up in the test situation does not ensure that people would enjoy it under different circumstances.

e$.$ Most people do not drink soda in order to perk themselves up$.$