Option 1 states that total internal reflection occurs when light travels from a rarer to denser medium with no loss of intensity. However, this is incorrect. Total internal reflection actually occurs when light travels from a denser to rarer medium.

Option 2 correctly states that total internal reflection occurs when light travels from a denser to rarer medium with no loss of intensity. This means that if the angle of incidence is greater than the critical angle, all the light will be reflected back into the denser medium instead of being refracted out into the rarer medium.

Option 3 states that total internal reflection occurs when light travels from a rarer to denser medium, but with a loss of intensity. This is incorrect as total internal reflection is characterized by no loss of intensity.

Option 4 states that total internal reflection occurs when light travels from a denser to rarer medium, but with a loss of intensity. This is also incorrect, as total internal reflection does not result in any loss of intensity.

To summarize, option 2 is the correct answer as it accurately describes total internal reflection – it occurs when light travels from a denser to rarer medium without any loss of intensity.