The distance of the plane $\overrightarrow{r}.\bigg(\frac{2}{7}\hat i+\frac{3}{7}\hat j-\frac{6}{7}\hat k\bigg)$=1 from the origin is

Question

$$(A)\;1 \qquad (B)\;7 \qquad (C)\;\frac{1}{7} \qquad(D)\;None\;of\;these.$$