The correct answer is option 2, Ear. The smallest bone found in the human body is known as the stapes or stirrup bone. It is one of the three tiny bones called the ossicles that are located in the middle ear. These three bones, including the malleus or hammer bone and the incus or anvil bone, are responsible for transmitting sound vibrations from the eardrum to the inner ear. Among these three bones, the stapes is the smallest and measures about 2.8 to 3.3 millimeters in length. It is shaped like a stirrup, hence its name. The stapes bone is crucial for hearing as it helps to amplify sound waves and transmit them to the cochlea, which is the sensory organ for hearing in the inner ear.