Total internal reflection occurs when light travels from a denser medium to a rarer medium, with an angle of incidence greater than the critical angle (Option B). This optical phenomenon happens because the refractive index of the denser medium is higher, causing light to slow down. As the angle of incidence increases, there is a specific angle, called the critical angle, at which the refracted light would travel along the boundary. When the angle of incidence exceeds this critical angle, no refraction occurs, and all the light is reflected back into the denser medium. This reflection is known as total internal reflection. It is utilized in various applications, including optical fibers, where light signals are transmitted over long distances with minimal loss. The principle also explains phenomena like the sparkling effect in diamonds and the functioning of certain types of prisms.