Which of the following nerves originates from the brain?

The brain originates from which germ layer?

How many pairs of cranial nerves in mammals are purely sensory?

$P$ - Contains unmyelinated nerve fibers.
$Q$ - Contains myelinated nerve fibers.
$I$ - Spinal nerves
$II$ - Autonomic neural system
$III$ - Somatic nerve fibers
$IV$ - Cranial nerves
Select the correct option for $P$ and $Q$.
$\quad\quad P$ $\quad$ $\quad$ $Q$

What is the visceral nervous system?

The $PNS$ (Peripheral Nervous System) comprises: