The electric field of a plane polarised electromagnetic wave in free space at time t = 0 is given by an expression.\({\rm{E}}\left( {x,y} \right) = 10{\rm{\hat jcos}}\left[ {\left( {6x + 8z} \right)} \right]\)The magnetic field B (x, z, t) is given by (where, c is the velocity of light)

• A. \(\frac{1}{c}\left( {6{\rm{\hat k}} - 8\hat i} \right){\rm{cos}}\left[ {\left( {6x + 8z + 10ct} \right)} \right]\)
• B. \(\frac{1}{c}\left( {6{\rm{\hat k}} - 8\hat i} \right){\rm{cos}}\left[ {\left( {6x + 8z - 10ct} \right)} \right]\)
• C. \(\frac{1}{c}\left( {6{\rm{\hat k}} + 8\hat i} \right){\rm{cos}}\left[ {\left( {6x - 8z + 10ct} \right)} \right]\)
• D. \(\frac{1}{c}\left( {6{\rm{\hat k}} + 8\hat i} \right){\rm{cos}}\left[ {\left( {6x + 8z - 10ct} \right)} \right]\)