Solution:

The direction of propagation of an electromagnetic wave is given by the cross product \(vec{E} \times \vec{B}\). For wave propagation along the positive \(x\)-direction, the cross product must yield a positive \(hat{i}\) vector. Using option C, \((-\hat{j} + \hat{k}) \times (-\hat{j} - \hat{k}) = \hat{j}\times\hat{k} - \hat{k}\times\hat{j} = 2\hat{i}\), which satisfies this condition.