The correct answer is A. ( + 1 and -1).
A normal distribution is a continuous probability distribution that is symmetric about the mean, with the mean, median, and mode all equal. The standard deviation measures how spread out the data are, and a normal distribution with a standard deviation of 1 is said to be “bell-shaped.”
The expected return is the average of the possible returns, and it is often used as a measure of the central tendency of a probability distribution. A normal distribution with an expected return of 0 is said to be “centered at 0.”
The options B, C, and D are all incorrect because they do not represent the range of possible values for the expected return of a normal distribution. The expected return of a normal distribution can be any real number, but it is most commonly between -1 and 1.