A unit vector is coplanar to the vector \(\vec{a}\) = l̂ + ĵ + 2k̂ and \(\vec{b}\) = l̂ + 2ĵ + k̂ and perpendicular to the vector \(\vec{c}\) = l̂ + ĵ + k̂, is
1
\(\frac{{\hat l - \hat j}}{{\sqrt 2 }}\)
2
\( \pm \left( {\frac{{\hat j - \hat k}}{{\sqrt 2 }}} \right)\)
3
\(\frac{{ - \hat l + \hat k}}{{\sqrt 2 }}\)
4
\( \pm \left( {\frac{{\hat i + \hat j + \hat k}}{{\sqrt 3 }}} \right)\)