The boundary condition at the surface of incidence obeys ________

• A. Kepler‚Äö√Ñ√∂‚àö√ë‚àö¬•s law
• B. Gauss law
• C. Faraday law
• D. Snell‚Äö√Ñ√∂‚àö√ë‚àö¬•s law