Which of the following is not a part of the human central nervous system?

Consider the following statements regarding the human brain:
$1.$ The cerebrum has a highly convoluted surface,which provides space for more neurons.
$2.$ The medulla oblongata is connected to the spinal cord.
$3.$ The medulla oblongata contains centers for respiration,cardiovascular reflexes,and gastric secretions.
Which of the above statements are correct?

Assertion : The brain stem contains centres for controlling activities.
Reason : Brain stem is very sensitive.

The third ventricle of the brain is called:

Which of the following is $NOT$ an effect of the sympathetic nervous system?

Distinguish between:
$(1)$ Sensory nerve and Motor nerve.
$(2)$ Corpus callosum and Ciliary body.