Which set of vitamins is considered neurotropic (essential for nervous system health)?

$A$: $Hydra$ has a nerve net but no brain.
$R$: All its neurons are apolar and connected.

Which of the following systems in man is affected by the bite of a cobra?

Pioneer work on conditioned reflex was done by

Arrange the following in the correct sequence in the evolution of the nervous system:
$(a)$ Formation of a centralised nervous system.
$(b)$ Diffused nervous system in $Hydra$.
$(c)$ Formation of a ganglion.
$(d)$ Nervous system is lacking in sponges.

Which of the following systems are involved in the regulation and coordination of the human body?
$I -$ Digestive system
$II -$ Endocrine system
$III -$ Excretory system
$IV -$ Nervous system
$V -$ Reproductive system