When a ray of light passes through an equilateral glass prism :

The correct option is D

both (b) and (c)

The explanation for the correct option

(d) both (b) and (c)

For option (b)it suffers refraction on both the refracting surfaces

1. When a ray of light passes through the prism there is a change in medium, it goes from a lighter to a denser medium due to which refraction occurs.
2. Now, when it leaves the prism there is again a change in a medium which is from denser to lighter medium.
3. So, refraction occurs on both the refracting surfaces.

For option (c) it bends towards the base on both refracting surfaces

1. Again when light passes from a lighter medium to a denser medium it bends towards the base due to a change in the medium.
2. This process takes again when it leaves the prism.

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The explanation for the incorrect option:

(a) it suffers refraction on the first refracting surfaces

When light enters the prism, it gets refracted at two surfaces.

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Thus, when a ray of light passes through an equilateral glass prism it suffers refraction on both the refracting surfaces and it bends towards the base on both refracting surfaces.