Final Answer:
The bone that forms the lower jaw is the mandible (Option 3).
Step-by-step explanation:
The mandible is the largest and strongest facial bone, constituting the lower jawbone in humans. Functionally, it houses the lower teeth and aids in various essential activities like chewing, speaking, and facial expressions.
Anatomically, it connects to the skull at the temporomandibular joint, allowing movement for functions such as chewing and speaking.
The mandible's significance lies in its pivotal role in the structure and functionality of the lower facial region, contributing not only to the framework of the face but also to essential processes like speech and mastication.
Option 3 is the right answer.