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

Which of the following is a requirement of the probabilities assigned to the outcomes $O _ { i }$ ? $\begin{array}{|l|l|}\hline A&P\left(O_{i}\right) \leq 0\\\hline B&P\left(O_{i}\right) \geq 0\\\hline C&0 \leq P\left(O_{i}\right) \leq 0, \text { for each } i\\\hline D&P\left(O_{i}\right)=1+P\left(\bar{Q}_{i}\right)\\\hline\end{array}$