$\text{ Let }A\text{ and }B\text{ be two events. Suppose }P\left(A\right)=0.4,P\left(B\right)=p\text{, and }P(A\cup B)=0.7\text{. The value of }p\text{ for which }A\text{ and }B$

$\text{ are independent is }$

• A

  $\frac{1}{3}$

• B

  $\frac{1}{4}$

• C

  $\frac{1}{2}$

• D

  $\frac{1}{5}$