The use of the word "vocabulary" serves primarily to A. demonstrate the presence of a rudimentary grammatical structure in canary song B. point out a similarity between the patterned groupings of sounds in a canary's song and the syllabic structures of words C. stress the stability and uniformity of canary's song throughout its lifetime D. suggest a similarity between the possession of a repertoire of words among humans and a repertoire of songs among canaries E. imply that the complexity of the canary's song repertoire is equal to that of human language