Taser and smell combine to cause you to experience:

The taste of a food if not being smelt, combines at the back of the throat and a lingering of smell can be experienced internally to the nose.

Explanation:

The taste and smell use the same environmental molecules and receptors. The odor of a substance is the molecules that we breathe through the air. The taste and smell unites at the back of the throat.

If we taste something before smelling it, the smell of that substance lingers into our nose internally as they both use the same chemo-receptors.  The receptors while coming close to the stimulus get activated and sends signal to the brain to respond to it.  

it should be d) transitional fossils.

they show the gradualism of evolution throughout a period of time