In a normal distribution, which of the following statements is true about the area that falls between one standard deviation above and one standard deviation below the mean? It contains the bottom 50% of the distribution. Answer A: It contains the bottom 50% of the distribution. A It contains the middle 50% of the distribution. Answer B: It contains the middle 50% of the distribution. B It contains the bottom 68% of the distribution. Answer C: It contains the bottom 68% of the distribution. C It contains the middle 68% of the distribution. Answer D: It contains the middle 68% of the distribution. D It is the same as the square of the average deviation.