No need to show work just give correct answer please

Which one is correct? [2K] * 2 points O The total internal reflection is NOT possible when a wave travels from a high to a lower index of refraction. O The total internal refraction occurs when the angle of incidence is equal to the critical angle. O The angle of incidence and reflection might be different when a straight wave meets a straight barrier. )When a light ray enters a medium with a 90 degree angle, refraction does not occur. How can we decrease the speed of an electromagnetic wave? [2K] * 2 points O The speed of electromagnetic waves is always constant O By moving to a medium with a higher index of refraction By decreasing the wavelength By increasing the frequency What is the maximum amount of opening for a wave diffraction to be 2 points observable? [2K]* ON2 O 2X O A ON4