Which of the following statement concerning the system of classification in taste is TRUE
A．The writer feels upset that there is no better system of classification than the familiar one of sweet, sour, bitter, salty。
B．Psychological perception of the taste is objective because no subjective judgement is involved.
C．It is extremely difficult to classify smell, as it's hard to make objective judgement on the stimulus.
D．The classification is subjective, for there is no relation between the perception and the stimulus.