Seven white balls and three black balls are randomly placed in a row. The probability that no two black balls are placed adjacently equals

Question

$\begin {array} {1 1} (A)\;\large\frac{1}{2} & \quad (B)\;\large\frac{7}{15} \\ (C)\;\large\frac{2}{15} & \quad (D)\;\large\frac{1}{15} \end {array}$