Suppose John scores 70 on a standardized self-esteem scale A and Bill scores 50 on a standardized self-esteem scale B. Scale A has a mean of 60 and a standard deviation of 20, and scale B has a mean of 80 and a standard deviation of 10. Assuming that a higher test score indicates a higher self-esteem on each of the two scales,which of the following statements is NOT an appropriate conclusion about comparing the two boys' level of self-esteem.

A. We don't know if John has more self-esteem than Bill based on this information.

B. We don't know based on this information alone because the two scales are different.

C. We should subtract each scale's mean from each raw score and then divide by each scale's standard deviation.

D. If scale A had a mean of 60 and a standard deviation of 20, and if scale B had a mean of 80 and a standard deviation of 10, then John has more self-esteem.