6. Which of the following statements about normal distribution is (are) correct?(AB) The graph used to depict a normal distribution consists of a symnetrical bell-shaped curve.(AC) The bell-shaped curve is a common feature of nature and psychology.(AD) Normal distributions may not be symmetric around their mean.(AE) Normal distributions a are defined by two parameters. the mean and the standard deviation, only.(BC) The arca under the normal curve is equal to 100.(BD) The tails of normal distribution curves are asymptotic. They meet the horizon (i.e. x-axis).