If $A$ And $B$ Are Mutually Exclusive Events With $P(A)=\frac{1}{7}, P(B)=\frac{2}{7}$ , Then $P(A \cup B)$

Multiple Choice

If $A$ and $B$ are mutually exclusive events with $P(A) =\frac{1}{7}, P(B) =\frac{2}{7}$ , then $P(A \cup B)$ equals

A) $\frac{3}{7}$ .
B) $\frac{19}{49}$ .
C) $\frac{2}{47}$ .
D) 0 .