Read the following statements carefully and select the correct option:
$I.$ The medulla is connected to the spinal cord.
$II.$ Medulla contains controlling centres for respiration,cardiovascular reflexes and gastric secretion.
$III.$ Cerebellum has a very convoluted surface in order to provide the additional space for more neurons.

• A
  $I$ and $II$
• B
  $II$ and $III$
• C
  $I$ and $III$
• D
  $I, II$ and $III$