When Figuring a Correlation Coefficient,scores Are First Converted to Z

Multiple Choice

When figuring a correlation coefficient,scores are first converted to Z scores because

A) the standard deviation is the same for every variable.
B) scores can never be more than 2 standard deviations from the mean.
C) all scores are on a consistent 0 to 1 scale.
D) high scores are positive numbers,and low scores are negative numbers.