Answer : 2. "3"
Explanation :

The mammalian middle ear contains three ossicles, which move the vibrations of the eardrum into waves in the liquid and membrane of the inward ear. There are three ossicles in every ear : Malleus, Incus, Stapes. As we have a couple of ears, so altogether there are 6 ossicles, or 3 sets of ossicles.