The correct option is C Mesencephelon
Midbrain is the rostral part of the brain stem, which includes the tectum and tegmentum. It is involved in functions such as vision, hearing, eye movement and body movement. The anterior part has the cerebral peduncle, which is a huge bundle of axons traveling from the cerebral cortex through the brain stem and these fibers are important for voluntary motor function. Therefore, option C is the correct answer.