When unpolarized light is incident on a Tourmaline crystal of proper thickness
a) it exhibits dichroism
b) it absorbs ordinary ray and transmits extraordinary ray
c) it absorbs extraordinary ray and transmits ordinary ray

Some transparent crystals, such as tourmaline and calcite, have the property that when one views an object through them one sees two images of the object. If one passes a narrow beam of light through them, the refracted beam is split into two parts which travel through the crystal and emerge as two separate beams. One of the beams obeys the ordinary laws of refraction and is called the ordinary ray. The other beam is called the extraordinary ray. 

It absorbs ordinary light and transmits extra ordinary light of different colours. When a beam of plane polarised light is incident normally on a plate of tourmaline cut parallel to the optical axis, it will be absorbed or transmitted depending on whether the axis of tourmaline is parallel or perpendicular to the plane of polarisation of the incident light. The ordinary light is parallel to the axis and thus it is absorbed and extraordinary light is perpendicular which is transmitted by it.

The extraordinary ray does not always lie in the plane of incidence. Its speed, and consequently its index of refraction, depends on its direction of propagation through the crystal.
Since the speed of the emerging rays and angle are different, the emergent rays are circularly or optically polarized.
Hence both ordinary and extraordinary light are transmitted.