**Given:**
- Refractive index of the prism = 2
- Incident ray just grazes the second face of the prism

**To find:** Angle of deviation

**Solution:**

The angle of deviation is the angle between the incident ray and the emergent ray.

Let's consider a ray of light incident normally on the first face of the prism. Since the incident ray is normal to the surface, it will not deviate and will pass through without any change in direction.

1. Incident Ray:
- Angle of incidence (i) = 0 degrees
- Angle of refraction (r) = 0 degrees (since the incident ray is normal to the surface)

2. Refracted Ray at the first face:
- Angle of incidence (i') = 0 degrees
- Angle of refraction (r') = 0 degrees (since the incident ray is normal to the surface)

Now, the refracted ray at the first face will be incident on the second face of the prism.

3. Incident Ray on the second face:
- Angle of incidence (i") = 0 degrees (since the incident ray is normal to the surface)

The refractive index of the prism is given as 2. The refractive index is defined as the ratio of the speed of light in vacuum to the speed of light in the medium.

Refractive index (n) = c/v
where c is the speed of light in vacuum and v is the speed of light in the medium.

Since the refractive index of the prism is 2, the speed of light in the prism will be half of its speed in vacuum.

4. Refracted Ray at the second face:
- Angle of incidence (i") = 0 degrees (since the incident ray is normal to the surface)
- Angle of refraction (r") = 0 degrees (since the refractive index is 2, the speed of light in the prism is half of its speed in vacuum)

As the refracted ray just grazes the second face of the prism, it emerges parallel to the base of the prism.

5. Emergent Ray:
- Angle of incidence (i'") = 0 degrees (since the refracted ray just grazes the second face)
- Angle of refraction (r'") = 0 degrees (since the refracted ray just grazes the second face)

Since the angle of incidence and angle of refraction are both 0 degrees, the emergent ray will be parallel to the incident ray. Therefore, the angle of deviation is 0 degrees.

Hence, the correct answer is option A) 0 degrees.