Which of the following statements are true about probability mass functions? Explain why each statement is true or false.
a. P(X = x) can be 1 for a particular value of x.
b. The graph of P(X = x) must be non-decreasing.
c. P(X = x) can be negative for a particular value of x.
d. P(X = x) can be 1 for more than one particular value of x.
e. P(X = x) can be zero for a particular value of x.
f. P(X = x) can be zero for infinitely many values of x.
g. P(X = x) can be strictly positive for infinitely many values of x.