Which of the Following Is a Requirement of the Probabilities $O _ { i }$

Multiple Choice

Which of the following is a requirement of the probabilities assigned to the outcomes $O _ { i }$ ?

A) P(Oi) ? 0.
B) P(Oi) ? 0.
C) 0 ? P(Oi) ? 0, for each i.
D) P(Oi) = 1 + P( $\bar { O } _ { i }$ ) .