# If M and N are any two events,the probability that at least one of them occurs is

$\begin{array}{1 1}(A)\;P(M)+P(N)-2P(M\cap N)\\(B)\;P(M)+P(N)-P(M \cap N)\\(C)\;P(M)+P(N)+P(M \cap N)\\(D)\;P(M)+P(N)+2P(M\cap N)\end{array}$

Probability that atleast one event occurs is
$P(M \cup N)=P(M)+P(N)-P(M \cap N)$
Hence (B) is the correct answer.