An assignment of probabilities must obey which of the following?
(a) The probability of any event must be between 0 and 1, inclusive.
(b) The sum of probabilities of all outcomes in a sample space must be exactly 1.
(c) Then event is the sum of the outcomes in the sample space that make up the event.
(d) all of the above.
(e) only (a) and (b) are true.