Axons form nerves in

Choose the correct pair:

What is the visceral nervous system?

$P$ nerve fibers transmit impulses from tissues/organs to the $CNS$ and $Q$ nerve fibers transmit regulatory impulses from the $CNS$ to the concerned peripheral tissues/organs.
$\quad\quad\quad P\quad\quad\quad Q$

The somatic neural system relays impulses from the $CNS$ to the ........

The brain is derived from which embryonic germ layer?