"If you were conducting a study and looking at a standard deviation of std=0, what would that mean about your data?

"If you were conducting a study and looking at a standard deviation of std=0, what would that mean about your data?"

A There is too much variability within the data and multivariate outliers need to be examined

B "There is no variability in the set of scores, it's a constant"

C "It is impossible to obtain std=0, you did something wrong with your data"

D The data points are at variable but equally incremental distances from the mean