A-ray of light travelling from a rarer medium to a denser medium

The correct answer is to slow down and bend towards the normal.

Key Points

Refraction

• It is the bending of light rays after entering a medium where its speed is different.
• Due to the refraction of light, when a ray of light passes from a rarer medium to a denser medium, bends towards the normal boundary between the two media. The amount of bending depends on the indices of refraction of the two media. 
• A ray of light traveling from a rarer medium to a denser medium slows down and bends towards the normal. Hence, Option 2 is correct.
• When it travels from a denser medium to a rarer medium, it speeds up and bends away from the normal.
• The angle of refraction or the amount of bending of light depends on the refractive index (μ) of the two media.
• When light passes through a low refractive index, like air (faster medium or optically rarer medium) to a high refractive index, like glass(slower medium or optically denser medium), its speed decreases and bends towards the normal. 
• When light passes through a high refractive index, like glass (slower medium or optically denser medium) to a low refractive index, like air (faster medium or optically rarer medium) its speed increases and bends away from the normal.