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(B) The electromagnetic wave propagates along the $+ve$ $X$-axis. The electric field $\vec{E}$ is in the $-ve$ $Z$-direction $(\vec{E} = -E_z \hat{k})

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(B) The electromagnetic wave propagates along the $+ve$ $X$-axis. The electric field $\vec{E}$ is in the $-ve$ $Z$-direction $(\vec{E} = -E_z \hat{k})$. According to Maxwell-Ampere's law,$\oint \vec{B} \cdot d\vec{l} = \mu_0 \epsilon_0 \frac{d\phi_E}{dt}$.Since the magnitude of the electric field is increasing,the electric flux $\phi_E$ through the rectangle is increasing in the $-ve$ $Z$-direction. By Lenz's law,the induced magnetic field will oppose this change.Using the right-hand rule,the magnetic field $\vec{B}$ must circulate in a way that creates a flux in the $+ve$ $Z$-direction to oppose the increasing $-ve$ $Z$-flux. This corresponds to a counter-clockwise circulation of the magnetic field around the rectangle.Furthermore,since the wave is travelling in the $+X$ direction,the field values are higher at positions closer to the wave front. Thus,the magnetic field magnitude will be relatively larger at the edge further along the $X$-axis compared to the edge closer to the origin. Diagram $B$ correctly depicts this counter-clockwise circulation with a larger magnitude on the right edge.

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