JEE Math Practice Question

The length of the perpendicular drawn from the point (2, 1, 4) to the plane containing the lines $$\overrightarrow r = \left( {\widehat i + \widehat j} \right) + \lambda \left( {\widehat i + 2\widehat j - \widehat k} \right)$$ and $$\overrightarrow r = \left( {\widehat i + \widehat j} \right) + \mu \left( { - \widehat i + \widehat j - 2\widehat k} \right)$$ is :

1. A.$${1 \over 3}$$
2. B.$${1 \over {\sqrt 3 }}$$
3. C.3
4. D.$${\sqrt 3 }$$