Which of the Following Statements About a Discrete Random Variable $\Sigma$

Multiple Choice

Which of the following statements about a discrete random variable and its probability distribution are true?

A) Values of the random variable can never be negative.
B) Some negative values of f(x) are allowed as long as $\Sigma$ f(x) = 1.
C) Values of f(x) must be greater than or equal to zero.
D) The values of f(x) increase to a maximum point and then decrease.