The neural canal develops from which of the following germ layers?

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.

Select the correct arrangement of neural organization,according to the increasing degree of complexity.

$A-$ Humans can sense changes in the environment.
$R-$ Sensory organs detect all types of changes in environment.

The ability to perceive a stimulus and enter a state of activity is a property of a nerve fiber. It is called:

Dreaming occurs in