At First,Pavlov Was Reluctant to Study the "Psychic Secretions" of His

At first,Pavlov was reluctant to study the "psychic secretions" of his laboratory dogs because:

A) he lacked the proper kinds of laboratory apparatus.
B) he thought the variables could not be sufficiently well-controlled.
C) he was more interested in active, instrumental behaviors than in passive responses such as salivation.
D) he was afraid of being associated with psychology, which he regarded as a scientifically disreputable subject.