A.
The author first refutes the classification of research and then criticizes the intellectual snobbery and tendency to look down on the one of the two.
B.
The author first refutes the classification of research into the pure and the applied and then presents his own classification.
C.
The author first refutes the classification of research and then points out that the classification results from two false ideas.
D.
The author first points out the practical importance of applied research and then criticizes those who look down on applied research.