Concept:Total internal reflection is the complete reflection of light inside a denser medium when its angle of incidence at the boundary with a rarer medium exceeds the critical angle.Explanation:i. Correct. The critical angle is obtained using refraction of light at the boundary, so total internal reflection is linked to refraction.ii. Incorrect. This phenomenon occurs when light travels from a denser medium to a rarer medium, not into a denser medium.iii. Correct. Total internal reflection takes place when the angle of incidence just exceeds the critical angle.iv. Correct. When the critical angle is exceeded, the light ray is completely reflected back into the denser medium.Answer:D. i, iii and iv only