Nature of EM Waves & Wave Equation question from JEE Main 2012 (AIEEE)

Nature of EM Waves & Wave Equation

• (a)$\vec{X}\parallel\vec{B}$ and $\vec{X}\parallel\vec{B}\times\vec{E}$
• (b)$\vec{X}\parallel\vec{E}$ and$\vec{k}\parallel\vec{E}\times\vec{B}$
• (c)$\vec{X}\parallel\vec{B}$ and$\vec{k}\parallel\vec{E}\times\vec{B}$
• (d)$\vec{X}\parallel\vec{E}$ and$\vec{k}\parallel\vec{B}\times\vec{E}$