Transparent samples of the mineral calcite can exhibit double refraction. When placed over an object, the image of the object appears to be doubled.

What causes the pencil to appear to be doubled?

Responses

The light is reflected twice by the calcite.
The light is reflected twice by the calcite.

The light bends around the edges of the calcite.
The light bends around the edges of the calcite.

The light is bent into different directions by the calcite.
The light is bent into different directions by the calcite.

The light bounces around and then is blocked by the calcite.

The light is bent into different directions by the calcite.