The Probability of an Event $A \text { or } B ( \operatorname { Pr } ( A \text { or } B ) )$

The probability of an event $A \text { or } B ( \operatorname { Pr } ( A \text { or } B ) )$
to occur equals

A) $\operatorname { Pr } ( A ) \times \operatorname { Pr } ( B )$
B) $\operatorname { Pr } ( A ) + \operatorname { Pr } ( B ) \text { if } A \text { and } B \text { are mutually exclusive. }$
C) $\frac { \operatorname { Pr } ( A ) } { \operatorname { Pr } ( B ) }$
D) $\operatorname { Pr } ( A ) + \operatorname { Pr } ( B ) \text { even if } A \text { and } B \text { are not mutually exclusive. }$