What May NOT Be Said About the Mean of a Discrete

Multiple Choice

What may NOT be said about the mean of a discrete random variable x?

A) It is denoted by.
B) It is the middle value of its probability distribution.
C) It is denoted by E(x) , because it is the value of x one can expect to find, on average, by numerous repetitions of the random experiment that generates the variable's actual values.
D) It is correctly described by both (a) and (b) .