सही विकल्प है (B) \(\hat j\)
Formula to be used: \(\vec n = \vec a \times \vec b\) and \(\hat n = \frac{\vec n}{|\vec n|}\) where it is the unit vector perpendicular to both vectors \(\vec a \) and \(\vec b\).
\(\vec n = (\hat i + \hat k) \times (\hat i - \hat k) = \begin {vmatrix} \hat i & \hat j& \hat k\\1&0&1\\1&0&-1 \end{vmatrix} = -\hat j (-1 -1) = 2\hat j\)
\(\hat n = \frac {2\hat j}{\sqrt {2^2}} = \hat j\)