Margaret Took the Wechsler Adult Intelligence Scale (WAIS-III)and Was Told

Margaret took the Wechsler Adult Intelligence Scale (WAIS-III) and was told that she has an IQ of 90.Margaret is certain this proves that her teachers are grading her unfairly when they give her C's.Margaret's friend Latisha explained that an IQ of 90 is not the same as a grading of 90 percent.Instead,it means that Margaret's

A) score is actually at the 9^th percentile,which suggests that she is developmentally disabled.
B) score is actually above the 90^th percentile and her IQ is very high.
C) IQ test was invalid,since it is not possible to get a 90.
D) score falls below the mean and her IQ is slightly below average.