When light passes into a non-reflecting, non-absorbing medium, no energy is lost at the boundary. In particular: Energy flux is given by the (time-averaged) Poynting vector
→
S
=
→
E
×
→
H
For no reflection and no absorption, the tangential components of both fields are continuous across the interface: E1=E2,‌‌H1=H2. Hence the incident and transmitted fluxes are equal: S1=E1H1=E2H2=S2 Since all the energy that arrives is carried forward, the total energy carried by the wave remains the same. Answer: Option A (remains same).