In the context of the evolutionary history of single-subject designs, which of the following is true about the developments in the latter half of the 1960s?
A. A global measurement of therapeutic effectiveness was inappropriate because of the overwhelming complexity and number of confounding variables.
B. The aggregation power of group designs was preferred to the ability of single-subject designs to incorporate distinctiveness.
C. Awareness of the inadequacies of the uncontrolled case study led to the existence of the therapeutic professions being challenged.
D. The invention of descriptive and inferential statistics encouraged group comparisons.