In the Standard Deviation Approach to Analyze Data in Single

In the standard deviation approach to analyze data in single subject designs, the normal distribution is understood to have:

A) a chance zone that represents treatment scores not significantly different from baseline scores and this consists of scores that are within two standard deviations of the mean
B) a chance zone that represents treatment scores different from baseline scores
C) scores outside two standard deviations of the mean are inside the chance zone
D) when the data can be easily explained by chance, most scores will fall outside the chance zone